The Journal of Korean Art and Archaeology

Iron played a central role across much of Gaya (42–562) society, as reflected by the diverse range of iron artifacts recovered from the tombs of the confederacy’s elite. Above all else, iron provided the fundamental basis for its development. Gaya interacted with neighboring regions utilizing its iron production technology to manufacture and then trade in a wide array of iron implements. One group of items that stands out among Gaya’s iron artifacts is its armor, which consisted of body armor and helmets. More than half of the ancient armor excavated from sites dating to the Three Kingdoms period is attributable to Gaya. However, the large volume of suits of armor recovered from Gaya tombs should not be regarded as a direct indication of Gaya’s military might or the scale of its armed forces. Nevertheless, this rich material provides an important basis for understanding the types of armor manufactured in Gaya and the nature of the technology that was involved in their production. In addition, clues to the distinctive world-view of ancient Gaya communities can be gleaned from the armor and the ways in which it was utilized in different social contexts. Although Gaya armor is rich in data and has great historical significance, studies on ancient Korean armor (including that of Gaya) have been sorely lacking. The first serious study of Gaya armor was performed on an example excavated in 1917 from Marisan Tomb No. 34 in Haman. A detailed analysis could not be performed since the armor was recovered in a partial and fragmented state. The pieces of armor were merely identified as such, and their existence was recorded in the published excavation report. Although the excavation of Marisan Tomb No. 34 and the publication of the related excavation report took place during the period of Japanese occupation and no Korean archaeologists were involved in the research process, the significance of this case study in the history of Gaya armor research should nevertheless be acknowledged. Subsequent research on Gaya armor took place sporadically, but full-fledged studies on Gaya armor only began to take place in the 1980s with the excavation of the Bokcheon-dong burial ground in Busan. Prior to this, the site of the manufacture of the armor excavated from Jisan-dong Tomb No. 32 in Goryeong had been a key matter of debate (Fig. 1). Due to its similarity to Wa-style armor (帶金式甲胄, the typical form of armor from the Japanese Kofun Period in which the helmet and body armor featured with long horizontal band design) frequently found in the Japanese Archipelago, this artifact was a subject of great interest within the Japanese academic community as evidence supporting the view of “Imna Ilbon-bu” (任那日本府) that considered Gaya territory to have once been under the control of Japanese forces. For this reason—its utilization in the obfuscation of ancient Korean history—the armor from Jisan-dong Tomb No. 32 was actually a subject of very little interest within the Korean academic community. On the other hand, great interest was directed at the finds of armor from the Bokcheon-dong burial ground since they represented the largest assemblage of armor collected in a single burial ground and because the vertical iron plates of which it was composted made it a type distinctive to Korea. It was, therefore, only following the investigation of the Bokcheon-dong burial ground that a full-fledged discussion of the origins, development, and background of ancient Korean armor began to take place (Jeong Jingwon & Shin Gyeongchul 1984). The subsequent excavations of major Gaya burial grounds such as the Daeseong-dong burial ground in Gimhae, the Okjeon burial ground in Hapcheon, and Dohang-ri burial ground in Haman resulted in the accumulation of a considerable body of data on Gaya armor. This made it possible for Gaya armor to develop into a research topic of considerable significance as with Gaya pottery or horse gear, and studies have actively been conducted on its characteristics and the changes in its attributes over time (e.g., Song Gyehyeon 1988; Kim Yeongmin 2000; Song Jeongsik 2008; Jang Gyeongsook 1999; Kim Hyuk-joong 2009). Fig. 1. Wa-style Body Armor and Helmet. Excavated from Jisan-dong Tomb No. 32 in Goryeong. Gaya, 5th century. H. 40.6 cm, W. 49.6 cm (armor), H. 14.8 cm (helmet). National Museum of Korea The results of research on Gaya armor since the 1990s have revealed that Gaya communities began burying a large volume of armor as grave goods from an early date and sustained this funerary practice for a longer period of time relative to the other political entities of the Three Kingdoms period. Among Gaya’s neighboring kingdoms, Silla (57 BCE–935 CE) also began to bury armor as a form of grave goods from a relatively early date, presenting a fitting example for comparative analysis. However, crowns and other objects made from precious metals were more popular as prestige goods in Silla than was armor. In addition, there is the key distinction that armor decorated with gilt-bronze ornaments was more widely used as grave goods in Silla. In contrast, iron armor was interred more intensively and over a longer period of time in Gaya. This makes Gaya armor ideal for identifying the characteristics of and changes in the ancient armor of the Three Kingdoms period. In addition, the fact that many examples of ancient armor produced in the Japanese Archipelago have been recovered from Gaya tombs makes it useful for exploring the interactions and exchanges between Gaya and the ancient Japanese polity of Wa (倭). As mentioned above, horizontal plate armor has erroneously been applied in the past as evidence supporting the view of “Imna Ilbon-bu.” This type of armor should actually be regarded as a reflection of relations between ancient Korea and Japan. Indeed, armor originating from Gaya or produced on the Japanese Archipelago under the direct or indirect influence of Gaya technology has also been discovered at Japanese sites, and the meaning of its presence has been studied by both Korean and Japanese researchers (e.g., Uchiyama Toshiyuki 1994, Park Cheonsoo 2007, and Kim Hyuk-joong 2014). The Characteristics of Gaya Armor and Its Changing Nature over Time Most of the armor discovered at sites on the Korean Peninsula, including Gaya sites, is made of iron. However, armor was not always crafted from metals such as iron: organic materials such as wood or leather were also used to manufacture it. Unfortunately, the acidic soil conditions on the Korean Peninsula are unfavorable to the preservation of organic remains and make the recovery of armor made from organic materials unlikely. Nevertheless, there have been a few extraordinary cases in which the remains of armor made from wood or animal bone have been discovered amidst these unfavorable environmental conditions. Iron began to be used for armor in the fourth century during the transition from the Proto-Three Kingdoms period to the Three Kingdoms period. The majority of researchers believe that the development of weapons based on technological innovations and increased social conflicts provided the impetus for the adoption of metal materials for armor. The changes in the materials used to produce Gaya helmets and armor broadly mirror this trajectory. However, this paper focuses on the iron armor of the Three Kingdoms Period. Examination of the characteristics of Gaya helmets and body armor will therefore focus on iron examples. Helmets made using vertical plates, a technique observed throughout the world, were also present in Gaya. Introduced into Gaya via exchanges with the northern regions, these helmets can be divided into mostly two types: ones with “S-shaped” curved plates (彎曲縱長板胄, Fig. 2) and semi-globular ones with more straight, simpler vertical plates (Fig. 3). Seated at the uppermost point of the body, helmets are highly visible and tend to be more decorative than body armor. They appear to have been actively used to demonstrate distinctions in social status. The helmet could be extended and adorned with decorative features or a visor to block the sun. Fig. 2. Vertical Plate Helmet. Excavated from Yangdong-ri Tomb No. 78 in Gimhae. Gaya, 4th century. H. 43.5 cm, D. 22.0 cm. Gimhae National Museum Fig. 3. Vertical Plate Helmet. Excavated from Bokcheon-dong Tomb No. 44 in Busan. Gaya. H. 30.0 cm. Pusan National University Museum Vertical plate helmet was the typical type of the Three Kingdoms as well as of Gaya. It is diffcult to establish distinctive regional characteristics for this type of helmet, but those from Gaya stand out in terms of the decorative enhancement of the basic helmet structure, which resulted in the production of unique helmet styles. This decoration involved the application of gilt-bronze or the addition of ornamental elements. A representative example of an ornamented vertical plate helmet comes from Daeseong-dong Tomb No. 57. The cheek-covers of this helmet were adorned with fern-shaped motifs rendered by punching holes at evenly-spaced intervals. Helmets featuring a bill to shade the sun (similar to the baseball caps worn today) were also produced. These types of vertical plate helmets distinctive to Gaya appear to have had a great influence on the Japanese Archipelago. The origins of similar helmets recovered from Kannonyama Tomb in Gunma Prefecture and Ikenoue Tomb No. 1 in Fukuoka Prefecture have been traced back to the Korean Peninsula. The number of vertical plate helmets identified to date has increased gradually due to recent discoveries at the Wolsan-ri burial ground in Namwon and the Jisan-dong burial ground in Goryeong. Body armor made with vertical plates has been recovered from both Gaya and Silla sites, but examples have yet to be discovered at other sites in Northeast Asia. This has led it to be regarded as an indigenous type of armor that first appeared in the southern regions of the Korean Peninsula. Vertical plate armor is believed to have developed out of earlier wooden armor, with changes occurring mainly in terms of material. In addition to being unique to the southern reaches of the Korean Peninsula, this type of armor is significant in that it allows the technological standards of the era to be assessed and provides important information on how ancient Korean armor developed over time. Differences in terms of form can be observed between the vertical plate armor of Gaya and Silla. The former could be decorated with fern-shaped ornaments or others reminiscent of birds. Many examples feature a semi-circular gorget (Fig. 4). Silla vertical plate armor is characterized by horn-shaped gorgets, which distinguish it from Gaya vertical plate armor. Variations in the shape and structure of Gaya and Silla vertical plate armor can be seen as indicative of differences in the function and perception of armor. In particular, Gaya armor was not simply protective equipment, but also elaborately decorated gear for ceremonial purposes or to indicate status. On the other hand, Silla vertical plate armor was left undecorated and worn for practical purposes and replaced by lamellar armor at an early date. Fig. 4. Vertical Plate Body Armor. Excavated presumably from Toerae-ri in Gimhae. Gaya, 4th century. H. 70.0 cm, L. 33.0 cm, W. 30.0 cm. Gimhae National Museum Lamellar armor was made by interlinking hundreds of small iron scales with leather ties (Figs. 5 and 6). In contrast to vertical plate body armor, which is distinctive to Gaya and Silla, lamellar body armor was found throughout the Korean Peninsula and the wider Northeast Asian region. Lamellar armor consists of two types assembled (in terms of how the scales were connected) and worn in different ways. One type can be traced back to the Han people of China, and the other to the non-Han nomadic populations of the Northern Steppe regions. The latter type continued to be used well into the Joseon period (1392–1897) for its ease of wearing and superior defensive functionality. Fig. 5. Lamellar Helmet. Excavated from Bangyeje Tomb No. Ga-A in Hapcheon. Gaya. L. 6.8–8.0 cm, W. 8.0 cm (lamellar pieces). Jinju National Museum Fig. 6. Lamellar Body Armor. Excavated from Okjeon Tomb No. 43 in Hapcheon. Gaya. L. 10.0 cm, W. 2.6 cm (lamellar pieces), L. 74.0 cm (entire). Gyeong-sang National University Museum Gaya armor also included horse armor, mainly comprised of body armor and chamfrons (Figs. 7 and 8). Horse armor appeared following the widespread use of cavalry tactics in military strategy. More than any other type of equipment, horses played a key role in enhancing the fighting capacity of the army since the speed that they provided spread fear and brought disarray to an enemy’s ranks. The need to protect both the horse and its rider from attacks led to the emergence of heavy cavalry fitted with armor. The presence of the heavy cavalry in itself would have been enough to strike fear into an enemy. Fig. 7. Horse Armor. Excavated from Magapchong Tomb in Haman. Gaya, 5th century. L. 225.0 cm (entire). Gimhae National Museum Fig. 8. Chamfron. Excavated from Okjeon Tomb No. M3 in Hapcheon. Gaya, 5th century. L. 48.5 cm, W. 29.5 cm, H. 26.5 cm. Gyeongsang National University Museum Gaya Warriors as Seen through Armor Goguryeo (37 BCE–668 CE), Silla, and Gaya warriors were fitted with respective characteristic sets of armor. Known to its neighboring Japan as the “Golden Kingdom,” possibly due to their favor and usage of ornate gold and silver ornaments such as gold crowns, Silla even gilded their bronze armor. Many examples of this “gold-worked armor” have been recovered from tombs — especially the vambrace parts — including the South Mound of Hwangnamdaechong Tomb. As helmets and body armor made of gilt bronze are relatively fragile, they are unlikely to have been made to serve the original purpose of protecting the wearer against harm. Rather, as in the case of gold crowns, gold-worked armor would have been worn to enhance its wearer’s grandeur. Gaya armor also features additional decorative elements, the most distinctive of which can be found on vertical plate body armor. Much debate surrounds the function of Gaya vertical plate body armor. This is because its form varies widely the ornaments are far more elaborate compared to other types of Gaya armor, and the numerous connected plates used to make the armor vary so greatly in size that faulty cutting work has been considered. Those who maintain that Gaya vertical plate body armor served a utilitarian function (e.g., Lee Hyunjoo 2002) have highlighted the additional iron plates that have been found fixed to examples from Bokcheon-dong Tomb Nos. 38 and 57 and Daeseong-dong Tomb No. 57, which are interpreted as evidence of repair. On the other hand, those who argue that Gaya vertical plate body armor would have been used only in funerary contexts (e.g., Song Gyehyeon 1995) focus on the fact that the shape and form of the plates used to make the armor are not standardized. Gaya vertical plate body armor would have served a wide range of different functions, but recent studies have tended to concentrate on their ritual role. In some cases, gorgets were adorned with decorations in a bird motif or with animal fur (Figs. 9 and 10), which has been interpreted as an association with the tradition in which birds (who guided the deceased’s soul from this world to the next) were regarded as sacred beings (Oh Gwangseob 2004). Fig. 9. Vertical Plate Body Armor. Excavated from Bokcheon-dong Tomb No. 86 in Busan. Gaya. H. 68.0 cm, W. 34.0 cm. Gimhae National Museum Fig. 10. Vertical Plate Body Armor. Excavated from Daeseong-dong Tomb No. 2 in Gimhae. Gaya, 4th century. H. 66.0 cm, L. 40.0 cm, W. 31.0 cm. Gimhae National Museum Spiral patterns were also used as decoration. As symbols of the sun, the spiral patterns featured on Gaya vertical plate body armor may have served to deify the wearer as a sun-like being and expressed prayers for good fortune in warfare. Another possibility that has been proposed is that the vertical plate body armor was worn during ceremonies associated with rites of passage. The traces of repair, the lack of precision in the cutting of the iron plates, and the nature of the ornamentation have all been used as background to suggest that vertical plate armor was worn for rites of passage into adulthood (Song Jeongsik 2012). An association between the motifs of vertical plate armor and those of the weapon-like saw knife (有刺利器), which feature fern-shaped or bird-shaped barbs, has also been suggested. The vertical plate body armor recently recovered from Tomb No. II-43 of the Ga-dong burial ground in Busan, the most elaborately decorated example discovered to date, is adorned with bird, spiral, and line patterns along with animal fur as additional decoration. However, among other things, the primary function of helmets and body armor would be to protect the wearer during battle. As briefly examined before, the evolution of helmets and body armor over time is associated with the development of weaponry systems. Ancient weaponry can be divided, depending on their usage, into projectile weapons (which launch objects to far distances using projectiles) and pole weapons, with their lengths exceeding the height of a male warrior. The most representative weapons of each type would be the arrowhead and spearhead. Although relating to an earlier period, the accounts that appear in Sanguozhi (三國志, Records of the Three Kingdoms) and Jinshu (晋書, Book of Jin) concerning the superior spear-fighting skills of Jinhan and Mahan warriors can be used as a reference for reconstructing weaponry of that time. Armor and helmets, likewise, shows differences between the fourth-century products and the fifth-century ones with vertical plate armor being prevalent in the fourth century. Weapons excavated along with the vertical plate armor were mostly polearms including spearheads. Later on, as the length of arrowheads—projectile weapons—become elongated, their range distance was also extended (Jang Sanggab 2018). These lines of evidence illustrate that the infantry played a central role in military tactics at the time that iron armor first came into use in Gaya. The image of an ancient Gaya warrior and warhorse charging into battle, each fully suited in armor, easily comes to mind. Evidence of such heavy cavalry from the Three Kingdoms period has been found in the form of artifacts, textual accounts, and images on the walls of mural tombs. Information on the cavalry tactics of the Three Kingdoms period can also be obtained from ancient texts and Goguryeo mural tombs. Detailed studies of these sources have revealed that ancient military tactics either relied solely on cavalry or involved both infantry and cavalry. The pure cavalry tactics included single-combat tactics, ambush tactics, chase tactics, and shock tactics. Of these, the heavy cavalry was primarily involved in shock tactics. The widespread adoption of heavy cavalry in Gaya was associated more with the appearance of the saddle and stirrups to provide stability to the horse’s rider, compared to the bit, which was useful for controlling the horse. Lamellar armor was worn by the heavy cavalry, and the image of a heavy cavalry warrior in the murals of Goguryeo's Anak Tomb No. 3 shows that the rider’s suit of lamellar armor included additional elements such as a gorget (Figs. 11 and 12). It is likely that Gaya heavy cavalry was established by the fifth century given that chamfrons and horse body armor appear around this time along with saddles and stirrups. Fig. 11. Lamellar Body Armor. Excavated from Yeorae-ri Zone II Tomb No. 40 in Gimhae. Gaya, 5th century. L. 12.5 cm, W. 3.0 cm (lamellar pieces), L. 57.0 cm, W. 45 cm (entire). Gimhae National Museum Fig. 12. Lamellar Body Armor and Helmet. Excavated from Chilsan-dong Tomb No. 35 in Gimhae. Gaya, 4th century. L. 11.5 cm, W. 3.7 cm (lamellar pieces), L. 57.0 cm, W. 56 cm (entire). Gimhae National Museum The role of Gaya heavy cavalry in military tactics is, however, likely to have been limited. This can be gleaned from the type of tombs that have yielded artifacts associated with heavy cavalry. Rather than small- or middle-scale tombs, finds of chamfrons, horse body armor, saddles, and stirrups have been uncovered in large-scale tombs belonging to the ruling class of Gaya. This indicates that the segment of society that had access to the accouterments required for heavy cavalry was limited. Therefore, it is unlikely that Gaya operated a large-scale cavalry force or a concentrated heavy cavalry regiment, as was the case for Goguryeo or Baekje (18 BCE–660 CE). Rather, a small, simple class of heavy cavalry warriors that answered directly to the king or highest commanding officer would have likely existed in Gaya (Kim Hyuk-joong 2019). The Significance of Gaya Armor in Terms of World Heritage The characteristic features and changing nature of Gaya armor were briefly examined above, but it is also important to consider its significance from a wider perspective, particularly in terms of UNESCO World Heritage. The criteria provided by UNESCO may serve as guidelines for establishing the attributes considered to be of value from a World Heritage perspective: (ii) to exhibit an important interchange of human values, over a span of time or within a cultural area of the world, on developments in architecture or technology, monumental arts, town-planning or landscape design; (iv) to be an outstanding example of a type of building, architectural or technological ensemble or landscape which illustrates (a) significant stage(s) in human history. Research on Gaya iron artifacts including armor has explored a wide range of topics, including its origins, interactions and exchanges between polities, symbolism, and technology. A key feature of Gaya iron artifacts has been the presence of diverse elements being drawn to form a distinctive culture that owes much to the operation of networks. It should be noted that “networks” was also the theme of an international symposium hosted by the National Museum of Korea in 2019 to mark the opening of its special exhibition on Gaya. In one of the papers presented at this symposium, a critical examination was performed of previous approaches towards Gaya’s interactions and exchanges, and the need for an alternative perspective focusing on social networks was proposed (Kim Daehwan 2019). It was maintained that any analysis of Gaya’s ruling elite should also take into consideration the interactions that occurred between individuals and social groups, marking a significant step forward in Gaya studies. The analysis of the diachronic changes evident in these interactions has provided an apt window for examining the nature of the Gaya society. It cannot be denied that the establishment of networks through negotiations and exchanges between polities provided an important motor for Gaya’s development. For example, the relationship between Gaya and Wa, which was not one-sided but more mutual and formed through interactions taking place over an extensive period of time, played a significant role (Takata Kanata 2019). In particular, the “maritime village” concept newly suggested by Takata can be seen as an apt representation of a situation that prevailed at the time. Among Gaya’s trade goods, iron was the most important. Among its iron products, armor manufactured using the most sophisticated production technology was prominent. At the time, iron served as an important medium facilitating the operation and reproduction of networks within East Asia. Iron, therefore, provided the foundations for Gaya’s growth and generated Gaya the diverse formation of iron culture. It may be argued that, given this background, Gaya armor has sufficient merit to be considered a valuable asset to UNESCO World Heritage.

Gaya (42–562) was a polity centered in the southeastern region of the Korean Peninsula. Historical records indicate that it was established after the year 42 CE and survived for 520 years. It coalesced and developed during the Three Kingdoms period of Korean history, a period when the three ancient states of Silla (57 BCE–935 CE), Baekje (18 BCE–660 CE), and Goguryeo (37 BCE–668 CE) engaged in a continuous struggle to dominate the region. Gaya and Silla were located in the southeast and separated by the Nakdonggang River, the largest river in the southern reaches of the Korean Peninsula. Baekje was situated in the southwestern part of the peninsula. Although it is inclusively referred to as Gaya today, it was actually separated into several political entities that maintained unique respective cultures. The major centers of Gaya were Gimhae (Geumgwan Gaya), located around the Nakdonggang River estuary; Haman (Ara Gaya), located near the Namgang River, a western tributary of the Nakdonggang River; Goryeong (Dae Gaya), in the middle basin of the Nakdonggang River; and Goseong (So Gaya), abutting the southern coast. Historical records on Gaya are highly fragmentary, and the understanding of the history and culture of Gaya thus relies heavily on clues provided by archaeological research. The most representative archaeological data would be the abundant pottery excavated from the Gaya region. The aim of this article is to briefly introduce the pottery of Gaya. Although a more detailed summary of the accumulated results of research on Gaya pottery is needed, length constraints mean the article will simply highlight some of the major developments in Gaya pottery. To this end, the following text primarily examines the following: the significance of grayish-blue stoneware, which appears for the first time in the fourth century CE; the unique pottery production methods of Gaya; the mass production and distribution of jars; the wide diversity its kind; the appearance of stoneware in Japan; and influences on Gaya’s ceramics technology. The Appearance of Grayish-blue Stoneware and the Emergence of Gaya Pottery Gaya pottery can be divided between reddish-brown earthenware and grayish-blue stoneware. The reddish-brown earthenware vessels used in daily life gain a reddish color from being fired in open kilns. Their walls are relatively soft and easily absorb water. In contrast, grayish-blue stoneware vessels were mostly used as burial goods and storage vessels, and they took the form of dishes, pedestaled vessels, cups, and large jars. They were reduction fired at high temperatures in closed kilns to achieve vitrification and were tinged with gray or black. This grayish-blue stoneware began to be produced around the fourth century CE in the Gimhae area, the center of Gaya at the time. This is generally accepted as the genesis of Gaya pottery. Clearly, people in the Gaya region had made and used various forms of pottery prior to the appearance of grayish-blue stoneware, but these cannot be called distinctively Gaya pottery in terms of form or production techniques. Grayish-blue stoneware, however, was first produced in the Gaya region and was maintained long enough to become a distinguishing feature of the culture. This type of pottery developed in the Gaya region became widely distributed throughout the Korean Peninsula and parts of the Japanese Archipelago. This distribution vividly demonstrates the vigorous interactions between Gaya and its surrounding polities. Gaya pottery production techniques spread beyond their birthplace and had a major impact on the appearance and development of stoneware in Japan. Was the grayish-blue stoneware that marks the beginning of Gaya pottery an original invention of Gaya? Rapidly spinning potters’ wheels were used to shape grayish-blue stoneware, enabling mass production and the standardization of forms. Grayish-blue stoneware is characterized by its dense structure, solidity, and impermeability. The silica in the clay vitrified, as the pottery was fired in step kilns, reaching temperatures over 1200℃. Entirely new forms that had never been seen in previous wares suddenly appeared, such as jars with two lugs. Explanations of the origins of this new grayish-blue stoneware are largely divided into two hypotheses based on either adoption or independent innovation. Researchers who advocate the former focus on the similarities between two-lugged jars, one of the earliest examples of grayish-blue stoneware, and a type of Chinese porcelain. Much of the evidence pointing to Gaya’s active involvement in long-distance exchanges can be used to support the hypothesis of the adoption of pottery techniques from China. On the other hand, researchers have pointed out that the earliest grayish-blue stoneware from Gaya was not fired to vitrification (Fig. 1), and the development of this type of stoneware would have been impossible without local innovations and gradual improvements in firing technology. Thus, these views regard grayish-blue stoneware as an independent local technology. Fig. 1. Grayish-blue Stoneware Pottery. Excavated from Yangdong-ri Tomb No. 235 in Gimhae. Gaya, late 3rd–early 4th century. H. 32.0 cm. National Museum of Korea This is the earliest known example of grayish-blue stoneware pottery yielded by a tomb in Gimhae, which is located along the Nakdonggang River estuary. This lidded jar has an uneven surface resulting from sudden exposure to high temperatures. This appears to be the result of poor temperature control during firing. When discussing Gaya pottery, it is grayish-blue stoneware that first comes to mind. However, reddish-brown earthenware is also critical to understanding the pottery culture of Gaya (Fig. 2). Earthenware vessels were fired at relatively lower temperatures (less than 800℃) in an unsealed kiln, resulting in a reddish-brown shade, walls that are softer than stoneware, and high permeability. These wares consisted of pots, steamers, and bowls, and were used to boil water and other liquids, steam food, and as containers for foods. Grayish-blue stoneware has mainly been discovered in the context of burials, whereas reddish-brown earthenware has mostly been uncovered from dwellings rather than tombs. Although reddish-brown earthenware is thought to have been a remnant of pottery developed during the Bronze Age, the research conducted on this earthenware is scant compared to that on grayish-blue stoneware. There are a few reasons for this: A relatively smaller number of reddish-brown earthenware vessels has been excavated, and the evolution of the shape and the production techniques applied to these vessels over time remains unclear. Furthermore, no characteristics of this earthenware distinct to specific regions within Gaya have been identified. Fig. 2. Reddish-brown Earthenware. Excavated from Buwon-dong site in Gimhae. Gaya, 3rd–4th century. H. 15.0 cm (left). Gimhae National Museum On the other hand, grayish-blue stoneware shows obvious changes in the production techniques involved and can be considered a discrete innovation in pottery technology. Its forms are also unique compared to those found in other regions within Gaya and other countries of the time, and chronological changes in form and style are relatively clear. Gaya archeological sites have yielded a wide variety of artifacts, such as iron goods, pottery, and necklaces and earrings, illuminating the rich material culture of Gaya. The findings of goods that were imported from China and Japan reflect Gaya’s active involvement in international exchanges. Among the uncovered artifacts, grayish-blue stoneware is the most geographically widespread within Gaya and makes up the overwhelming majority. As a result, research has largely focused on grayish-blue stoneware despite the importance of reddish-brown earthenware as items of everyday use. This earthenware pottery is critical to forming a more holistic understanding of Gaya pottery. Unique Techniques for the Mass Production of Jars Gaya pottery is generally divided into an early and a late phase. The early phase refers to the first hundred years following the appearance of grayish-blue stoneware in the Nakdonggang River basin, up to about 400 CE. However, this new technology was not widely applied throughout the region at the time, and high-quality wares were only produced in certain areas. The two main production areas of pottery were Gimhae and Haman. Located at the mouth of the Nakdonggang River, Gimhae was the center of Gaya at the time. Haman is situated along the Namgang River, a tributary of the Nakdonggang River. Jars with mat-impressed patterns produced in Haman were also distributed over a large area spanning from the southern Korean Peninsula to the western Japanese Archipelago (Fig. 3). Various pottery forms such as mounted dishes, vessel stands, and cups were produced, but jars around 30 centimeters in height made up the majority. What were the reasons for the intensive production of this type of jar and its long-distance distribution beyond the Gaya territory? This question can be answered by understanding the character of this grayish-blue stoneware. Fig. 3. Jar with Mat-impressed Patterns. Excavated from Hwangsa-ri Tomb No. 44 in Haman. Gaya, 4th century. H. 28.3 cm. Gimhae National Museum Vessels for storing various liquids like water, alcohol, and other beverages were in demand at the time, but earthenware and wooden vessels were highly permeable. Although there were metal and lacquered vessels available at the time that could meet these functional requirements, they were rare, and their production would have been relatively difficult. In contrast, grayish-blue stoneware jars were impermeable and easier to manufacture in large quantities. This might be the reason why jar-shaped vessels were the dominant form of grayish-blue stoneware for the 100 years following their appearance. Kilns for producing early-phase Gaya pottery were most densely distributed in Haman area, and potters there employed unique methods for the mass production of jars. When vessels were fired, they were often nested and then stacked in the kiln to increase production capacity. Mostly, small, identical pieces like dishes or lids were so stacked, and this method was more generally applied in the latter phase of Gaya pottery production. Cases of placing one or two small vessels into a larger vessel have been found occasionally from the early phase, but the stacking method had not been fully developed. The reasons why they did not stack more pieces of pottery at that point in time can be considered in terms of the technology available and the experience of the potters, as well as supply and demand. If vessels were stacked up in many layers, heat circulation would have been disrupted by the mass of pottery within the kiln. To minimize the rate of failure and improve production under these conditions, experience with controlling the fire is critical. Perhaps the rationale for not stacking pottery at that time was simply the result of inexperience among the potters and the techniques available, given that it was still the very early stages of the development of grayish-blue stoneware. People were also less likely to apply the stacking method because the existing pottery supply was sufficient to meet the demand of the time. At the mouth of the Nakdonggang River, where the Gaya pottery was first produced, production and distribution both occurred within a narrow 25-kilometer radius. There are only a few rare exceptions in which this early form of grayish-blue stoneware has been discovered beyond that range. If demand was moderate and the pottery was only being distributed and used within a specific narrow area, there would be little need for the adoption of a new method. However, in Haman, where grayish-blue stoneware was being produced around the same time, jars were nested on their sides in the kiln and stacked up in two or three layers. This stacking technique was unique to Haman at the time. Stacking vessels like this enabled up to three times as many jars to be placed in the kiln, but it risked ruining the aesthetics of the pottery and increasing damage and the defect rate. Nonetheless, the potters of Haman employed this process of mass production by stacking and firing jars for up to 75 years. It was an assertive choice by the potters to invest more in production than in protecting the aesthetics of the pieces, which could be explained by the soaring demand for these highly useful type of vessel that could contain and store liquids. These mass-produced jars have been found in all of the regions associated with Gaya, in neighboring Silla and Baekje, and various parts of the Japanese Archipelago across Korea Strait. The Diversity of Gaya Pottery Gaya pottery underwent a remarkable transformation in terms of form and production technology around 400 CE. Before then, high-quality grayish-blue stoneware was produced only in select regions within the Gaya Confederacy, particularly near the mouth of the Nakdonggang River and in Haman. However, around the year 400, this technology spread not only across all the areas associated with Gaya, but to other polities as well, and various communities began to produce grayish-blue pottery. Based on the distribution of kilns at this time, both the technology and the potters involved appear to have moved in routes along the Nakdonggang River and southern coast, both of which were major transportation corridors. It is well known that Gaya was a confederation of several small and large polities, unlike the nearby kingdoms of Silla and Baekje. In each area associated with the Gaya Confederacy, ceramics began to be produced using these newly acquired techniques. However, each polity did not produce works of the same quality. At first, artisans produced pieces that were similar in form as they applied the adopted technology. However, it seems that many attempts at imitating this stoneware were unsuccessful: some examples have thick walls or failed during firing. Subsequently, individuals improved their skills gradually through trial and error and by inventing their own techniques. These production techniques were passed on to many regions in the southern Korean Peninsula, and the pottery culture of Gaya marked a novel transition as each Gaya polity came to possess highly-developed techniques. The appearance eventually shifted from more-or-less similar forms to assorted types reflecting the unique preferences of each Gaya polity (Figs. 4–7). The most popular form at the time, a mounted dish or vessel stand, vividly demonstrates variations in local preferences. Fig. 4. Geumgwan Gaya Pottery from Gimhae Region. Gaya. H. 25.0 cm (upper right). National Museum of Korea Fig. 5. Dae Gaya Pottery from Goryeong Region. Gaya. H. 39.0 cm (upper left). National Museum of Korea Fig. 6. So Gaya Pottery from Goseong Region. Gaya. H. 48.1 cm (right). National Museum of Korea Fig. 7. Ara Gaya Pottery from Haman Region. Gaya. H. 49.5 cm (upper right). National Museum of Korea These kinds of pottery were also common in Silla, but Gaya pottery can be distinguished by soft curves in the overall form and the unique design and decoration motifs. Under close examination, regional characteristics make it even possible to distinguish the Gaya polity that produced the wares. The diversity seen in these characteristics is a notable feature of Gaya pottery, although we generally refer to all of this pottery by the generic term “Gaya pottery” despite the variation. In the latter stage of Gaya pottery, when diversity increased, mounted dishes, lids, and vessel stands were produced in large quantities, and jars lost their predominance. These items were not made for daily life but for use as ritual goods. Some of the pottery itself would be interred, but a considerable amount was simply used to hold offerings at burial rituals. There are several examples in which fish bones, conch shells, and chicken bones have been found in wares inside Gaya tombs. The use of diverse pottery forms by different polities for their burial rituals and the mass production of pottery in each area hold special implication. Burial rituals might be a simple behavior for mourning the dead, but standardized rituals in particular communities can have multiple and complex meanings related to the cohesion of the community, the display of wealth or social and political status, and the legitimation of the succession of power. The eventual use of similar forms of pottery for burial rituals across all of Gaya's polities can be interpreted as strengthening the political and social relations among them. By this time, the size of tombs had gradually expanded within the Gaya territories, and increasingly larger amounts of pottery were being buried. This change in customs crucially affected the demand for burial pottery, such as mounted dishes, and increased demand for burial pottery resulted in the development of new tools and techniques. To produce more wares in shorter periods of time and within space constraints, potters transitioned towards stacking pottery layer by layer in the kiln. This technique eventually became common throughout Gaya. In other words, the techniques to produce pottery more efficiently were developed further, and this information was shared across communities. Novel forms appeared in Gaya around the start of the later stage of its pottery, roughly the year 400. Among these are vessels with atypical shapes and others that were modeled after the forms of assorted objects. This figurative work was diverse, including vessels that mimicked animals such as birds, horses, and deer; objects in the form of houses, boats, shoes, and wagons; and warriors on horseback (Fig. 8). Special meanings seem to have been ascribed to various objects from the surrounding environment, such as horses, which were a valuable resource in warfare. Boats were used for maritime trade and along rivers. Shoes and wagons were used for mobility and transportation. Pottery also took on the shapes of structures important for an agrarian society, such as granaries. Object-shaped pottery was imbued with various meanings in Gaya, allowing us to infer that various kinds of rituals that took place. Moreover, this pottery also provides a snapshot of the houses, boats, wagons, shoes, and warriors of Gaya that cannot be reconstructed through artifacts or historical records. Fig. 8. Horn Cup in the Shape of a Warrior on Horseback. Excavated presumably from Deoksan-ri in Gimhae. Gaya, 5th century. H. 23.2 cm. Gyeongju National Museum. National Treasure No. 275 Gaya Pottery and the Appearance of a New Pottery Culture in Japan In some parts of the Japanese Archipelago, a new type of pottery known as sue ware (須惠器, Jp. sueki) appeared about the time of the beginning of the latter phase of Gaya pottery (Fig. 9). Sue ware was characterized by highly distinct forms and techniques relative to earlier types of Japanese pottery, so it is considered an innovation in both the ceramic and cultural history of Japan. The appearance of sue ware closely parallels the timing of the emergence of grayish-blue pottery in Korea. It was produced using techniques new to the Japanese Archipelago that resulted in hard, dense walls with good water retention due to firing at high temperatures. It must have been a dramatic improvement to be able to contain and store fluids (alcohol, water, etc.), which had been impossible with previous wares, and so most sue ware forms were designed for containing liquids. This transition can be seen in the earliest known sue ware kilns, which mostly produced enormous wares with a capacity of over 300 liters of liquid. Functional divisions emerged according to the different characteristics of types of pottery. For example, sue ware was used primarily for holding liquids, whereas reddish-brown earthenware, called haji ware (土師器, Jp. hajiki) in Japan, was mainly reserved for cooking. Fig. 9. Early Sue Ware. Excavated from Obadera site in Suemura Kiln site. Kofun Period. H. 5.0–32.0 cm, D. 10.0–42.0 cm. Osaka Center For Cultural Heritage It is widely accepted that pottery technology from the Korean Peninsula influenced the epochal appearance of sue ware. Surveys have uncovered early sue ware kilns in Osaka and Nara close to the center of royal authority in western Japan. Suemura in Osaka is considered a type site for sue ware kilns. With about 1,000 kilns, it is the largest pottery-producing site discovered in Japan and was in operation for 500 years starting in the fifth century CE. Due to the large volumes that have been excavated, Japanese sue ware has been well chronicled since 1950s. In particular, pottery produced in the earliest known kiln at the site caught the attention of researchers because it clearly shows the influences of Gaya pottery in terms of form, decorative designs, and shaping techniques. Sue ware, resembling Gaya pottery, began to be turned out using potters’ wheels and high-temperature firing in a climbing kiln. Of course, not every product was simply a reproduction of Gaya pottery, and pottery forms and crafting techniques that had previously existed in Japan are also observed in sue ware along with forms from other regions on the Korean Peninsula. Thus, this site may demonstrate a circumstance in which a group of people who crafted pottery crossed over to the Japanese Archipelago around 400 CE and produced wares using this site as a center. As mentioned earlier, the pottery-production technology of Gaya played a definitive role in the appearance of stoneware in Japan. Although opinions differ regarding the motivations for related artisans to have traveled to Japan, one thing is certain: there were clearly continuous and close exchanges between Gaya and Japan. Epilogue The characteristic features of Gaya pottery become increasingly notable with the arrival of grayish-blue stoneware, which was first crafted around the Nakdonggang River estuary starting in the late third to the early fourth century. The first such stoneware was made up of jars suitable for containing and storing liquids. People in Haman applied a unique technique that allowed for the mass production of jars, and Gaya pottery was distributed over a wide area beyond the Gaya sphere. Subsequently, stoneware production technology was transferred and applied to diverse areas, and a wider variety of forms emerged that clearly reflected the identity of the Gaya polity in which they were produced. Moreover, rather than being applied to everyday use, grayish-blue stoneware was intensively produced as burial goods for tombs, which were growing increasingly larger in size. At the same time, the ceramic production technology of Gaya had a major influence on the appearance of a new pottery culture in Japan. Archaeologists rely on ceramics more than any other type of artifacts to draw inferences about the passage of time and aspects of regional change. Thus, studying pottery is one of the most popular areas within archaeological research. Scholars of Gaya have achieved great progress, and the results of their work have been accumulated to build specific chronologies that can be utilized as critical data for studies of other subjects. Even so, it is true that data from pottery is insufficient to achieve the true purpose of archaeology: reconstructing the cultures of the past. This essay introduces Gaya pottery based on archaeological data, although it is undeniably insufficient to provide a full understanding of the culture.

A pair of white birch bark mudguard flaps featuring a now-famous image of a heavenly horse was discovered in 1973 during the excavation of Cheonmachong Tomb (Cultural Heritage Management Bureau, 1974). These flaps, which were likely applied as saddle attachments, were designated National Treasure No. 207 in 1974. Cheonmachong Tomb is a royal tomb located in Gyeongju, the capital of the Silla Kingdom. Originating in the southeast corner of the Korean Peninsula, the ancient kingdom of Silla endured for 992 years from 57 BCE to 935 CE. It is known that Cheonmachong Tomb was constructed in the early sixth century, but the identity of its occupant remains a mystery. Mudguard flaps are used to keep a rider’s garments clean and protect the rider from injury. They also help to prevent harm to the horse from the stirrups. Mudguard flaps were valuable objects that were included among prestige or grave goods by the Silla royalty and aristocracy, as evidenced by their discovery in Cheonmachong Tomb and Geumryeongchong Tomb (Chang Youngjoon 2015a, 62-73). However, the study of mudguard flaps (and particularly of their production process) has been limited due to the minimal number of related finds. The image featured on the mudguard flaps from Cheonmachong Tomb, on the other hand, has been intensively examined (Moon Gyeonghyun 2006, 1-38; Lee Songran 2002, 71-106; Lee Jaejoong 1991; 1994, 5-41; 2000, 23-59; 2002, 423-441), and it can now be identified with confidence as portraying a heavenly horse and not a Chimera Qilin (Chang Yongjoon 2015b, 74-95). Little is known about the mudguard flaps from Cheonmachong Tomb apart from the fact that they were made from the bark of a white birch tree and that they feature a painted image. The flaps were found with one on top of the other. The heavenly horse image widely known among the public comes from the flap placed beneath. This lower flap was in a relatively good state of preservation since it had been protected by the flap on top. Conservation work had not previously been performed on this upper flap, but it was undertaken in preparation for the “Cheonmachong, a royal tomb of Silla” Special Exhibition organized by Gyeongju National Museum in 2014 and for the publication of Mudguards with Heavenly Horse Design from the Cheonmachong Tomb of Silla in 2015. This provided an opportunity for the study of the production method of both the upper flap and lower flap to take place. This paper intends to examine the characteristics of the white birch bark used in the flaps in order to explore how mudguard flaps were manufactured during the Silla period. The dating of the wood that provided the bark will also be considered. Various experimental and observational methods were applied to establish how the mudguard panels were made and to identify any differences that may exist between the images on the respective flaps. Three-dimensional scanning technology was also utilized in order to reconstruct how the mudguard flaps would have appeared at the time of their manufacture. Mudguard Panel Dimensions and Materials The two flaps are respectively referred to as the upper flap and the lower flap (Figs. 1–6) according to their position at the time of discovery. Each mudguard flap was made using three pieces of bark (one large and two small pieces). Fig. 1. White birch bark mudguard flap from Cheonmachong Tomb (upper flap). Silla. Bark. Gyeongju National Museum Collection Fig. 2. Infrared photo of the upper flap Fig. 3. White birch bark mudguard flap from Cheonmachong Tomb (lower flap). Silla. Bark. Gyeongju National Museum Collection Fig. 4. Infrared photo of the lower flap Fig. 5. White birch bark mudguard flap from Cheonmachong Tomb (upper flap) Fig. 6. White birch bark mudguard flap from Cheonmachong Tomb (lower flap); The mudguard flap featuring a heavenly horse image widely known in Korea Mudguard Flap Panel Dimensions The front panels of both the upper and lower flap were each made from a single piece of bark. The back panels, in contrast, were made by connecting two pieces of bark, each of which was slightly larger than one-half of the front panel piece. The measurements for the panel pieces differ according to the point being measured, but the general dimensions are as follows. The front panel of the upper flap, in its extant state, measures 73.4×54.7 centimeters. The back panel measures 72.6×52.6 centimeters. Of the two pieces forming the back panel, the left is 44×52 centimeters, and the right is 54.5×38.4 centimeters. The thickness of the front and back panels of the upper flap combined is 4–8 centimeters. The thickness of a given piece of bark can vary at different points due to the natural peeling of the surface or its intentional trimming during manufacture. The mudguard flap panels are irregularly shaped due to the shrinkage of the bark components, making it difficult to precisely measure their dimensions. However, measurements taken with a ruler and thread to accommodate the curved surfaces of the bark make it possible to estimate that the mudguard flap would have been 75.0 centimeters high, 56.8 centimeters wide, and 0.81 centimeters thick at the time of its production, slightly larger than its current size. The thickness of the front and back panels attached together is approximately 4.5 millimeters. However, at its thickest point, along a vertical line through center, the flap measured approximately 7–8 millimeters. This is the area where the two bark pieces forming the back panel overlap so the flap consists of three sheets of bark. The front panel of the lower flap measures 73.2×55.2 centimeters in its present state. The left and right bark pieces forming the back panels measure 39.1×52.4 centimeters and 39.5×52.6 centimeters, respectively. The combined thickness of the front and back panels of the lower flap measures around 4–8 millimeters, varying at different points as in the case of the upper flap. It is estimated that the mudguard flap would have been 74.2 centimeters high, 56.0 centimeters wide, and 0.8 centimeters thick at the time of its production. Based on the above, it can be established that the two mudguard flaps were similar in size at the time of their manufacture. Mudguard Flap Materials and Characteristics In the excavation report for Cheonmachong Tomb, the mudguard flap was identified as having been made from the bark of a white birch tree. The surface of a tree is conventionally covered by an outer and an inner bark (also known as phloem) (Fig. 7). The inner bark is formed from live parenchyma cells that serve to transport and store photosynthates and are sometimes active in carbon fixation. The outer bark is made up of dead tissues or cork structures which serve to protect the inner bark.1 The bark panels of the Cheonmachong Tomb mudguard flaps were made from the outer bark of a white birch tree (Fig. 7). Fig. 7. Bark structure However, the outer bark used for the mudguard flap panels could not have been obtained from simply any convenient white birch tree. Ideally, bark should be obtained from a tree with a clean and even surface free from significant knots, as shown in Figure 8. Birch bark that peeled off in single or multiple layers, as birch bark characteristically tends to do, or that shows a dirty surface or an excess of knots would not have been suitable for crafting these mudguard flaps. Therefore, it can be surmised that few knots, limited peeling, and an absence of branches would have been important factors in selecting outer bark for the manufacture of the mudguard flaps. Fig. 8. The bark and knots of a birch tree (from a birch grove in Inje, Gangwon-do Province) (Photograph by the author in January 2004) Late April or early May when the sap is flowing is considered the best time to harvest the bark of a white birch tree. Outside of this season, it is impossible to obtain good quality outer bark from these trees. The clean state of the inner surface of the outer bark used in both of the mudguard flaps. The absence of traces of discharge from the inner bark indicate that the bark is likely to have been obtained during this sap flow period (Fig. 9). Fig. 9. Method of detaching bark from a white birch tree It is also important to estimate the age of the tree that provided the bark for the mudguard flaps, which can be done through an examination of tree rings. The thickness of the outer bark differs according to the growth conditions experienced by the tree, but if it is assumed that a new ring is formed each year, a supposition can be made regarding the age of a white birch tree by examining the layers of the outer bark.2 The layers of the bark used in the mudguard flaps were counted through microscopic observation. The thickness differed at points due to the natural peeling of the bark layers or as a result of human actions performed while processing the bark for use. In the case of both mudguard flaps, the bark forming the front panels was thinner than the bark used for the back panels. The bark used in the front panel of the upper flap consisted of 34–36 layers, which indicates that the bark came from a white birch tree at least 36 years old. The bark used in the back panel showed 48–50 layers, indicating that the tree that provided the bark was at least 50 years old. In the case of the lower flap, the bark of the front panel consisted of at least 41 layers, and the thicker back panel consisted of at least 52 layers, thereby indicating respective minimum ages of 41 and 52 years old for the white birch trees that provided the bark. The bark used for the back panels was thicker than that for the front panels. The reason for this is unclear, but it could be that due to difficulty with obtaining bark of high quality for the front panels, the back panels were made using two pieces of bark. In this regard, using thicker bark would have enhanced the strength of the panels and their ease of manufacture. The likelihood of this requires further consideration. Production of the Mudguard Flaps Connecting the bark pieces for the front and back panels 1. Overlapping the bark pieces for the back panel The two bark pieces forming the back panel were connected before it was attached to the front panel (Figs. 10–12). Fig. 10. The back side of the front panel of the upper flap (outer surface of the outer bark) Fig. 11. The back side of the back panel of the upper flap (inner surface of the outer bark) Fig. 12. The back side of the back panel of the lower flap (inner surface of the outer bark); the patterns observed are an imprint of the saddle blanket that was found beneath the lower mudguard flap at the time of its discovery Processing the bark cannot entirely obscure the lenticels. Traces of them can clearly be seen on the surface of the bark used for the mudguard flaps. The front panel of the lower flap features lenticel traces running vertically, whereas the traces on the bark pieces forming the back panel run in a horizontal direction as they would have originally been oriented on the tree. In the case of the upper flap, the inner surface of the outer bark was used for the front panel. The back panel was formed by placing two overlapping bark pieces (with the right-hand piece partially covering the left), and the entire panel was then stitched together at even intervals (Fig. 10). The back panel for the lower flap was made from two overlapping outer bark pieces with the inner surface facing outwards; this formed the back of the mudguard flap. The two bark pieces overlap by approximately 4.5–5.5 centimeters, with the right piece partially covered by the left and the overlapping area loosely stitched together. A thread consisting of two strands of fibers, similar to that used to attach the front and back panels of the mudguard flap, was applied to stitch together one-third of this overlapping section. The remaining two-thirds of the overlapping section of the back panel was stitched together using a single-fiber thread. 2. Combining the front and back panels The bark used in the lower flap shows a greater number of traces of large knots compared to the upper flap. In particular, the back panel features larger knot traces, and the state of its surface is in a poorer condition compared to the front panel, possibly because the front side of the back panel would have been covered by the front panel and not exposed. It is the front side of the front panel, crafted from the inner surface of the outer bark, that features the painted image. If the bark surface had been left unworked, it would have been difficult to bind together two bark panels with their outer surfaces facing towards each other due to the uneven surfaces caused by knots. For this reason, the outer surfaces of the outer bark panels in both mudguard flaps were smoothed and flattened using a knife and other tools. Preventive measures were also taken to ensure that gaps did not appear between the two bark panels when they were bound together. It does not appear that any special adhesive was used when connecting the two pieces forming the back panel or when combining the front and back panels. In order to bind the two pieces more securely, the two panels were adjusted to ensure that their lenticels alternated (Figs. 11–12). A quilting method was used to combine the two bark pieces forming the back panel and the single bark piece forming the front panel. This establishes that the method of quilting using a running stich was applied 1,500 years ago. The stitching was performed by first carving grooved lines into the surface of the bark according to the intended final pattern. The width of the grooved lines was set so as to ensure that the threads did not protrude too much beyond the bark surface when the quilting had been completed. It is presumed that the grooves were cut into the surface using a metal tool such as a blunt knife. Given the thickness of the threads and the estimated size of the needle hole, it is also possible that the lines may have been established using the head of the needle. The stitching was executed at intervals of 0.2–0.4 centimeters. Each stitch is of a regular length (approximately 4 millimeters) and was made in a diagonal direction. Fourteen quilted lines run at an angle of approximately 45 degrees from the upper right to the lower left, and 15 quilted lines run from the upper left to the lower right. This is the case for both of the mudguard flaps. The stitching did not involve the prior punching of holes for the needle to pass through; the holes were made by the needle at the moment of stitching. This can be established based on the fact the holes were observed to have been punched in alternating directions (as can be seen from their shape), which is to be expected when using a running stitch (Fig. 13). The stitching technique can also be established based on the shape of the holes: The needle first pierced the panel in an upward direction and then in a downwards direction. Fig. 13. Sewing traces and direction as seen in the cross section of the mudguard flap Each section of the diamond-shaped pattern that was formed by the quilting tends to be around 6 centimeter long, although the lengths vary in between 5.5–6.0 centimeters. This level of regularity indicates that the intersecting intervals of the grooved lines for stitching were carefully measured beforehand. Efforts were made to follow the grooved lines when stitching, but there were instances in which it was not properly observed and stitches strayed from the line. The grooved lines would have marked the place where the needle was to have penetrated the bark panel. It can be observed from the lower flap that the direction of the stitches for the individual quilting lines could differ when required. The stitching directions in the upper flap and lower flap were found to vary (Figs. 14–15). In addition, there appears to have been no particular pattern to the knotting of the thread, as can be seen from the lower flap. It is possible to observe that the thread was knotted where it ran out or unexpectedly broke. Fig. 14. Stitching direction used when quilting together the front and back panels of the upper flap Fig. 15. Stitching direction used when quilting together the front and back panels of the lower flap; the dotted circles denote the points where the stitches end and new stitches begin Framing the mudguard flaps The mudguard flaps were bordered using leather on top and silk underneath. Different bordering techniques were used according to the material. 1. Underlying silk border The silk used to border the mudguard flaps was a strip approximately 1.2 centimeter wide in the upper flap and 1.3 centimeter wide for the lower flap. The silk used to border the edges was fixed in place with stitches at intervals of approximately 5 millimeters. The silk was stitched to both the front and back sides of the flaps. Attempts were made, sometimes unsuccessfully, to align the stitches in a straight line. Observation of the boundary between the silk border and leather border reveals that the silk was covered by leather, which indicates that the silk was attached first. The absence of paint traces along the perimeters of the panel covered by the borders indicates that the mudguard flaps were bordered prior to their painting. Several different types of fibers were used (Park Seungwon 2015, 194-201). In the case of the upper flap, a warp-faced compound woven silk (經錦) of combined construction, which is a figured cloth, and hemp were used. The woven silk for the back side of the upper flap is the same as that for the front. The silk covered an area 1.2 centimeter wide along the perimeters of the flap. The hemp thread is a loose right-twist thread. Decorative thread was also applied, as was the case for the front side of the flap. This yellow thread has an average diameter of 0.17 millimeters and is a loose right-twist thread. 2. Leather border The upper edge and sides of the mudguard flaps were additionally bordered with leather 2.5–2.7 centimeters in width attached by weaving a leather cord through pre-punched rectangular holes (Figs. 16–17). The leather cord was 3.7 millimeter wide and 1.3 millimeter thick. Fig. 16. Detail of the stitches and the treatment of the leather frame edges of the upper flap Fig. 17. The stitches and the treatment of the leather frame edges of the upper flap The paired perforations for the leather cord form sets approximately 3 millimeters apart. In the underlying silk border, the distance between two stitches ranged from 1.3–1.5 millimeters. The holes were found to be located in a relatively regular manner. The type of leather used could not be identified, but deer leather, which is supple and easy to manipulate, was often used for horse harnesses at the time. The upper perimeters of the mudguard flaps were bordered with leather due to the gap between the front and back white birch bark panels, which made additional measures necessary in order to obtain a single edge. In addition, the leather served to protect the perimeters of the mudguard flaps from wear during use. The leather border also prevented the surface of the white birch bark from peeling off, which it tends to do, and restricted the bark panels from warping with fluctuations in temperature and humidity. Finally, the leather border also served to enhance the ornamental quality of the mudguard flaps. The thickness of the front and back panels attached together would have been substantial enough to allow the mudguard flaps to serve a practical function. Production of the image 1. Marking out the composition of the image The area where the painting was to be made was marked onto the surface of the white birch bark using a pointed implement, such as a knife. The impressions can still be observed beneath the painted layer on the mudguard flap. Two types of incised lines guided the painting: those that divided the inner from the outer border of the mudguard flap and the grooved lines that guided the quilting stiches joining the front and back pieces. The grooved lines for the quilting stitches played an important role in structuring the composition of the painting. The front side of the mudguard flap, which had been formed by combining the front and back panels, was composed of the inner surface of the outer bark layer of a white birch tree. The painting was made on this side. The background of the painting is a light yellowish-orange color, which is close to the natural color of the inner surface of the outer bark of a white birch tree, and it is quilted throughout. Pigment analysis carried out on this background revealed that it had not been painted. It is believed that this unpainted background would have originally been lighter in shade. Such a light background color would have been ideal for successfully expressing the white color of the cheonma (天馬, heavenly horse). 2. Painting the image 1) Types of pigments Previous analysis of the mudguard flap paintings and the bird painting (瑞鳥圖彩畵版, seobongdochaewhapan) from Cheonmachong Tomb revealed the use of white, red, and black pigments. Traces of malachite, which produced a green color, were also found (Yoo Hyeseon and Shin Yongbi 2015, 202-205). No remains of pigments were observed on the background of the mudguard flaps, indicating that it had been left unpainted. Four pigments were used in the painting on the flap: white lead for white, cinnabar for red, black from an ink stick, and malachite for green. The red appearing in the Cheonmachong Tomb mudguard flap paintings and the bird painting was found to have been produced using a mixture of white lead (Pb) and cinnabar (Hg). In contrast, the red used in a horse-rider painting found in the tomb was produced by mixing iron oxide and lead. Similarities in the color composition and theme of the Cheonmachong Tomb mudguard flap paintings and the bird painting suggest that they were created using the same pigments. 2) Producing the image It had previously been believed that the surface onto which the heavenly horse images were painted was the outer surface of the outer bark of a white birch tree. However, it was possible to confirm that the surface was in fact the inner surface of the outer bark. The inner and outer surfaces of the outer bark could be distinguished through differences in the knots, lenticels, color, and state of the epidermis. The images were painted onto an inner surface in the case of both the upper and the lower flap. On the upper flap, attempts appear to have been made to avoid areas with knots while painting the images. Compared to the lower flap, the knots on the upper flap are smaller and less prominent. The lower flap, on the other hand, features relatively large knots, even on the front side where the image of the heavenly horse was produced. The rear portion of the horse is partially rendered over a knot. It is impossible to obtain birch bark strips that are entirely devoid of knots. However, the knots are less perceptible on the inner surface of the outer bark, resulting in a smoother surface. The inner surface of the outer bark also includes lenticels, but they are not highly visible through the painted surface and close inspection is required to identify them. The outer surface of the outer bark of the white birch tree requires treatment prior to painting since it tends to peel off in layers. This peeling can also occur naturally during the treatment, painting, and drying process. The inner surface of the outer bark, on the other hand, is smooth and of an even color, offering more favorable conditions for painting. The lenticels of white birch bark cannot be entirely erased, even when layers of bark are peeled away. A more advantageous base for rendering the painted image would have been obtained if the full surface of the bark panel had been treated with a background color, but this was not the case. In addition to the risk of the bark peeling, one possible reason for the lack of a background may have been considerations related to the pigments. One of the four colors employed was a white produced with white lead. This white pigment was used for the key image on the mudguard flap, the white heavenly horse, and the lotus flowers as well. This white heavenly horse could not have been properly expressed against a white surface on the birch bark. It is therefore possible to presume that the painter limited the use of white pigments to ensure that the white heavenly horse would provide the focus of interest. It is likely due to such considerations, along with the condition of the bark surface and the characteristics of the pigments, that the mudguard flap paintings were rendered onto the inner surface of the white birch bark. The painting sequence was as follows: peripheral images were produced first (this can be established based on the relationship between the hoof of the left foreleg and the right foreleg of the horse, and the peripheral lotus-flower patterns nearby), followed by the heavenly horse, and finally the four lotus buds featured within the lotus-flower pattern boundary. Black pigments were applied first in the painting of the lotus and arabesque pattern, followed by red and then by white. 3) Comparing the images of the upper and lower flap The two mudguard flaps each featuring an image of a heavenly horse were attached one at either side of the saddle. It is interesting to note that each horse was painted facing in the same direction, which would have meant that when the mudguard flaps were attached to the saddle, one of the horses would have faced forwards while the other faced backwards. In order to identity the differences between the two heavenly horses on the mudguard flaps, the two images were rendered in different colors and overlapped (Fig. 18). It can be observed that the two images are broadly similar in terms of composition. The interior space framed by the band of patterns running along the boundary of the flap features images of a heavenly horse, clouds, and lotus flowers. The peripheral band consists of lotus-flower and arabesque patterns, lotus-bud patterns, and mountain-shaped patterns. However, differences can be identified in terms of the detailed form and size of the patterns, as well as other factors. This merits further discussion. Fig. 18. Overlapped images of the paintings from the upper and lower mudguard flaps; the upper flap image is in blue and the lower flap image is in red Firstly, in the case of the heavenly horse image, both horses are similar in size but unique in terms of their detailed patterns. The horse on the upper flap has a somewhat slighter build, while the chest of the horse on the lower flap is expressed in a more voluptuous manner. The location and number of crescent shapes on the bodies of the horses are also similar. However, three locks of hair can be seen on the chest of the upper-flap horse, but not on the horse on the lower flap (Fig. 19). Fig. 19. Differences in the images of the upper and lower mudguard flaps In the case of the horse on the upper flap, the left leg is bent to nearly a right angle, whereas the left leg of the horse on the lower flap is bent further towards the body. In addition, the joints and hoofs of the upper-flap horse are expressed in a more angular manner. Various other minor discrepancies are apparent. Differences can also be identified in the location of the breath depicted as being expelled from the horses’ mouths. The ears of the horse on the lower flap are expressed in a clearer manner, and the mane decorations above the forehead are longer and rendered in a more dynamic style (Fig. 19-4). The tails are of a similar length, but their positions vary slightly (Fig. 19-7). There is one area where a noticeable distinction can be observed in the patterns: the fern-shaped expressions of condensation emanating from the horses’ bodies located between the rear leg and tail are curled in opposite directions (Fig. 19-8). It is between the lotus and arabesque patterns forming the peripheral bands of the mudguard flaps that the images diverge most significantly (Figs. 19-1, 19-2). The upper portion of the peripheral band of the upper flap consists of seven arabesque and lotus-flower sections, but only six are apparent in the lower flap. The starting positions of the arabesque and lotus-flower sections also differ: the lotus-flower section furthest to the left points upwards in the case of the lower flap, but downwards in the upper flap (Fig. 19-1). The lower portion of the peripheral band consists of an equal number of arabesque and lotus-flower sections (six each) in similar starting positions for both the upper and lower flap. Based on this fact, it is possible that both the upper and lower parts of the peripheral band had been intended to contain six arabesque and lotus-flower sections. Due to the slightly smaller size of the arabesque and lotus-flower motifs in the upper part of the peripheral band of the upper flap, an additional section had to be added in order to fill the gap in the band of patterns. The fact that the arabesque and lotus-flower section located second to the left on the upper part of the peripheral band of the upper flap is considerably smaller than the other sections provides evidence for this supposition. In addition, a single lotus bud can be found between the second- and third-left arabesque and lotus-flower sections in the lower flap, which is lacking in the upper flap (Fig. 19-1). As can be seen in section 9 in Figure 19, some of the lotus buds have their petals expressed while others do not. In the case of both mudguard flaps, the left portion of the peripheral band consists of four arabesque and lotus-flower sections. However, the uppermost flower faces to the left in the upper flap and to the right in the lower flap. The size of the individual arabesque and lotus-flower sections also differs: The sections of the lower flap are slightly larger than those of the upper. The right part of the peripheral band demonstrates the greatest degree of uniformity in terms of the number, size, and positioning of the arabesque and lotus-flower sections. The only difference is the unique addition of lotus buds on the left part of the peripheral band of the respective flaps. Based on the above, it can be considered unlikely that the images of the two flaps were produced by the same person. Clear differences can be seen in the detailed brushstrokes in the paintings and the techniques applied. However, it is difficult to know for certain whether the paintings referenced a common base sketch with the differences stemming from faulty execution. It would be expected that the appearance of the heavenly horse or the orientation of the peripheral band patterns would be the same if a base sketch had been referenced, but this is not the case. What is clear is that if both are copies of the same image, then one was a less-than-faithful reproduction. The attachment of horse ornaments The horse ornaments attached to the mudguard flaps are all heart-shaped. The existence of these horse ornaments was unknown before their discovery during the preservation and reconstruction process. The rings of the ornaments were made of iron covered with gilt bronze. The central portion of the ornaments includes a silver covered heart-shaped design to enhance their decorative function. Each mudguard flap featured a pair of ornaments that were attached at the final stage of production. Production of a replica of the mudguard flaps Three-dimensional scanning, infrared photography, X-ray photography, and observation with the naked eye were performed on the lower flap, which was relatively well preserved relative to the upper flap. These processes were used to craft a reproduction of the mudguard flap in its original state (Figs. 21–22). Fig. 20. Diagram of the production process of the mudguard flaps Fig. 21. Creation of polygon meshes Fig. 22. Polygon mesh of the mudguard flap information Firstly, due to the uncertainty surrounding the original shape of the mudguard flap (given that it may have warped after it was buried), a detailed measured drawing of the mudguard flap was first produced using a 3-D scanner, and precise measurements were made to enhance the accuracy of the reproduction. Three-dimensional scanning was accomplished using a VIVID 910 scanner. The production of artifact drawings using a 3-D scanner has been widely applied to various artifacts on display, and the resultant information on the dimensions and colors of artifacts can contribute of the establishment of a database on such information. Three-dimensional scanning can involve direct and indirect contact; the Cheonmachong Tomb mudguard flap underwent the latter. The data obtained through 3-D scanning can be directly accessed through a computer. If any of the resulting measurements or other types of data were unclear, the scanning was repeated. In the case of curved surfaces, the optical displacement measurement sensor was moved to a second position to scan and obtain measurements from an additional direction. Following the completion of the scanning, the data was edited using Rapidform software to create CAD models. The polygon meshes generated using Rapidform software were compared with the X-ray images, infrared photos, and RGB data to make minor adjustments to the measured drawing, resulting in the final version. This measured drawing was compared with the actual mudguard flap, and color and detailed characteristics were then applied to produce a final reproduction (Fig. 23). Fig. 23. Proposed reconstruction of the lower mudguard flap Conclusion Various experiments and forms of observation were performed in order to establish facts concerning the production process of the Cheonmachong Tomb mudguard flaps, which had previously been unexamined. As a result, the following information could be obtained that provides important insights into the understanding of ancient cultures on the Korean Peninsula. First, the bark used in the mudguard flaps came from a white birch tree and not a Korean birch (Betula costata). It should be noted that white birch is not indigenous to the Korean Peninsula. Second, the mudguard flap image was painted on the inner surface of the outer bark rather than the outer surface. Third, the background of the image was not painted, and the natural color of the inner surface of the outer bark of the white birch tree was utilized. Four different pigments were used: white lead for white, cinnabar for red, an ink stick for black, and malachite for green. Fourth, the two heavenly horse paintings from the pair of mudguard flaps were not identical imitations of a single model. Their compositions are similar, but differences can be observed in the details of the iconography. It is possible that the pair of mudguard flaps may have been produced by the same person. However, given the complex nature of the detailed manufacturing process, a more likely scenario is that several people were involved in their manufacture through a division of labor. Fifth, the Cheonmachong Tomb mudguard flaps may be regarded as an assemblage of diverse technologies that were in use in the ancient Korean societies of the time. The manufacturing process of the mudguard flaps took place in ten stages from the preparation of the white birch bark panels to the attachment of the horse ornaments. Some of these phases were complicated and involved several steps. For example, two pieces of bark were required to craft the two front panels and four were needed to make the two back panels. Finally, a reproduction was created in order to reconstruct a pair of Silla mudguard flaps from the Three Kingdoms Period. These mudguard flaps would have been magnificent indeed at the time of their production. The heavenly horse is not only dynamic in nature, but almost seems to emanate a sacred aura. This work represents the first stages of further study on these mudguard flaps. Additional research will be undertaken in order to supplement the limitations of the current paper.