Integration and Transformation: A Study of the Sun and the Moon Depicted in the Imagery of Fuxi and Nüwa

The present research focuses on the depiction of the sun and moon in the imagery of Fuxi and Nüwa during the Han and Wei-Jin periods. Through typological and iconographical approaches, it proposes four primary modes in terms of the ways in which the sun and the moon are combined with Fuxi and Nüwa. It contributes to the current field by providing new perspectives for readdressing some issues that remain underexplored. First, it challenges the over-absolute identification of the earliest representation of Fuxi and Nüwa in a pair, and that of Changyi and Xihe, another set of paired deities recorded to be in close relation to the celestial world, in Western Han mural tombs from the Luoyang area, and instead suggests a shift of focus to the recognisable distinctions in visual details, such as the chronological sequence of the application of the first and second modes in the Luoyang Han tomb paintings, and the masculine appearances of both the deities depicted in the Western Han Qianjingtou tomb. Further examinations of the development and dissemination of each mode through the Han and Wei-Jin eras reveals complicated interactions between different regions and exchanges of motif with other forms of imagery. The local tradition of depicting Fuxi and Nüwa, together with that of the depiction of the sun and moon in Nanyang, has been incorporated into the formation of the sun and moon in anthropomorphic representations in the Southwest. Finally, this research proposes that it is more significant to organise the surviving materials through the development and context of each visual element represented in the scene, rather than making an absolute identification based on scattered evidence.


Introduction
Fuxi 伏羲 and Nüwa 女媧 were among the most prominent deities in Chinese genesis mythology. Fuxi is best known as an ancestor of human beings, and Nüwa is the goddess who created human beings by moulding yellow earth together and patching the broken sky. In visual culture, Fuxi and Nüwa usually appear as a couple with human faces and snake-like bodies that are sometimes intertwined with each other. Th e couple was frequently depicted on chamber walls of ancestral shrines ( Han (After Huang 1996, 73).
When it comes to the Wei-Jin 魏晉 tombs dated from the third to fourth centuries CE, the couple frequently appears on the covers of wooden coffins (Fig. 4), or pictorial bricks on tomb walls (Fig. 5). In the Tang Dynasty from the seventh to the ninth centuries, most of the depictions of the couple have been discovered at Turfan 吐魯番 in the Hexi Corridor 河西走廊, in the form of silk paintings that cover wooden coffi ns ( Fig. 6) (Deng 2010;Chen 2011). Th e union of Fuxi and Nüwa is considered like a diagram of yin 陰 and yang 陽, the two universal forces in the cosmology of the time, according to their diff erent genders and the usually intertwined bodies of the couple (Birrell 1993;Lewis 1999, 204;Wu 2012). In addition, the depiction of the sun and moon is generally considered a coherent visual component of the Fuxi and Nüwa imagery, appearing in the shape of round discs that contain a toad in the moon and a three-legged crow in the sun, respectively, since the Han Dynasty (Fig. 2, 3), while an abstract depiction of the sun with radiating beams inside and the moon in the crescent shape became dominant in Tang burial arts of the Hexi Corridor (Fig. 6).  Kong 2006, fi g. 14).   (After The British Museum, Museum no. 1928-1022).
However, the sun and moon are not always the standard attributes of Fuxi and Nüwa in the Han Dynasty, and sometimes are instead the compass and square ( Fig. 1), which are spread across the country, or the auspicious plant lingzhi 靈芝 (Fig. 7), particularly popular in the region of present-day Shandong and Nanyang 南陽 (in today's Southern Henan). How were the pair of the sun and moon integrated into the imagery of Fuxi and Nüwa? What was the specific significance of the sun and moon to Fuxi and Nüwa? And how to perceive the sun and moon in the larger iconographic scheme of the Fuxi and Nüwa? Moreover, how does the combination of the two pairs function in the ritual and burial contexts? These questions remain insufficiently examined in current scholarship. 1 1 Discussion of the connection between the two pair in major scholarships is very brief. There are monographic discussions on the depiction of the sun and the moon as celestial symbols and the two deities as a pair that possesses the power of fertility, but without any focused and thematic study of their connections. Th rough a thorough examination of the representations of Fuxi and Nüwa and that of the sun and moon from the Han to the Wei-Jin periods, the present essay proposes four primary modes in terms of the ways in which the two pairs are combined. Each mode shows a particular development of the imagery that includes both the pairs in specifi c historical and regional contexts. In the fi rst mode, the sun and moon appear besides Fuxi and Nüwa (Fig. 3). It is an "archaic" mode that was only found on ceilings of Western Han tombs from the then political and economic centre of the city of Luoyang (in today's northern Henan), and was not inherited by later traditions. Th e second mode refers to the arrangement of the sun and moon held in hands by Fuxi and Nüwa respectively. It could be termed "standard," as it is the most popular mode that has fl ourished through the long historical course of depicting Fuxi and Nüwa in a pair. In comparison to other modes, it is predominant in Nanyang (Fig. 8) and the Southwest (in today's Sichuan and Chongqing) (Fig. 2) during the Eastern Han, as well as the Hexi Corridor in the Wei-Jin era (Fig. 5). The third mode depicts the sun and moon as embraced in front of the chest of Fuxi and Nüwa. It was applied occasionally during the Han Dynasty in Shandong/Jiangsu ( Fig. 9), Nanyang ( Fig. 10), and Shaanxi ( Fig. 11), but not in the Southwest. During the Wei-Jin period, it became the predominant mode that was depicted on the surface of wooden coffins (Fig. 12) or pictorial bricks used in burials of the Hexi Corridor. Last, the fourth mode depicts the sun above Fuxi and Nüwa while the moon below ( Fig. 6), naturally in a vertical setting. Although it was applied primarily to silk paintings found in burials dated to the Tang from the seventh to ninth centuries, later than the time range of the current research, I include it since its prototype already appeared in the Wei-Jin era. Further iconographic analysis of the four modes within their contexts sheds light on revising issues remaining unclear in the identifi cation of Fuxi and Nüwa. Th e two deities depicted in the fi rst and second modes in Luoyang area appear to be more closely related to the legend of Changyi 常儀 and Xihe 羲 和, who were recorded as attendants of the sun and moon, instead of Fuxi and Nüwa. It discloses that the third mode, which has the sun and moon embraced by Fuxi and Nüwa, has exerted infl uence on the imagery of the sun god 日神 and moon goddess 月神, the anthropomorphic forms of the sun and the moon, in the Southwest region (Fig. 13).

Th e Sun and Moon in Literary Traditions
Th e sun and moon usually appear together as cosmic symbols. Th ey can be further interpreted respectively as representations of the essence of yang and yin that lay the foundation for the cosmogonic process of the creation of the universe. 2 Th e literary description of the sun's relation to yang and the moon's relation to yin becomes the primary evidence for scholars' interpretation of the integration of the sun and moon into the imagery of Fuxi and Nüwa. Fuxi and Nüwa have been associated with yang and yin in many sources. In Huainanzi 淮南子, it is the union of Fuxi and Nüwa that caused the process of the separation of Heaven and Earth, and thus the separation of yang and yin. Th e two deities were also recorded as the gods of the sun and moon, respectively (He 1998, 503-4).
Usually inside the moon is a hare or toad, and inside the sun a bird, or a more detailed three-legged crow. In Ling xian 靈憲 (Spiritual Constitution), it records that:

日者，陽精之宗，積而成鳥，象鳥而有三趾…月者陰精之宗，積 而成獸，象蜍兔。
Th e sun is the fundamental essence of yang. It accumulates into a bird that looks like a crow with three legs…The moon is the fundamental essence of yin. It accumulates into an animal that looks like a toad or a hare (Liu 1965, 3216).
In some sources, the three-legged crow is recorded as an attendant of Xiwangmu 西王母 (The Queen Mother of the West), without any association with the moon. 3 However, in the visual culture since the Western Han, the depiction of a three-legged crow in the sun usually appears in a pair with the moon.

In Between the First and Second Modes: Fuxi and Nüwa, or Changyi and Xihe
Examples that have been traditionally identified as the earliest representations of Fuxi and Nüwa are mural paintings from Han tombs near Luoyang in present-day Henan Province. 4 This group of murals share some essential characteristics, especially their locations on the central strip of the ceiling or the upper part of the walls in the burial chamber. Fuxi and Nüwa are identified according to their human faces and snake-like bodies, and the incorporation of the sun and moon, which is rendered in the first or second modes of representing the sun and moon as classified in this research. If we examine the chronology of these tombs, it is interesting to notice that mural paintings that applied the first mode are dated to the Western Han period, around the first century BCE, while those applying the second are from the later period (Huang 1996;Yang 2003;He 2001). For instance, the earliest burials, such as Bu Qianqiu 卜千秋 tomb (Fig. 3) and the Qianjingtou 淺井頭 tomb (Fig. 14,  15), applied the first mode, which depicts the sun and moon besides Fuxi and Nüwa, while tombs of the ) and Eastern Han (Fig. 17,18) in general adopt the second mode, which has the sun and the moon upheld respectively by Fuxi and Nüwa. It seems quite clear that the first mode was once preferred but later replaced by the second mode in the Luoyang area.      Nevertheless, this claim requires further discussion as it touches an issue that has been mentioned in some research but not yet addressed in detail: whether it is the pair of Fuxi and Nüwa, or Changyi and Xihe that are depicted in these tombs. Some research considers the couple depicted in the Xincun 辛村 tomb from the Xin-Mang period ( Fig. 16) and the Daobei shiyouzhan 道北石油站 tomb of the Eastern Han in the second mode as Changyi and Xihe (Fig. 17, 18). 5 In other words, it remains debatable about how to identify Fuxi and Nüwa in their formative stage during the Western Han Dynasty. Usually, figures were identified as Fuxi and Nüwa primarily because of their snake-like bodies, the symmetrical arrangement of them as a pair, or the attendance of the sun and the moon. However, the sun and moon could be associated with Changyi and Xihe, as Fuxi and Nüwa are not the only deities with snake-like bodies. Moreover, in the literary tradition, creatures with snake-like bodies are not explicitly associated with Fuxi and Nüwa. The silk manuscript from Zidanku 子彈庫 mentions that Fuxi looks like a dragon instead of a snake (Hunan sheng bowuguan 1974; Li 1985). Shanhaijing 山海經 (Classics of Mountains and Seas) records many creatures that feature a human-face and snakelike body. Nüwa and Xihe are just two of the many, and they are not in pair with any other male deities in most of these records (Yuan 1980, 230, 311).
Another issue involved in the identification of Fuxi and Nüwa is the origin of their combination into a couple. Although it was already a convention to render Fuxi and Nüwa as a couple, the origin of their combination remains debatable (Meng 2000;Hunan sheng bowuguan 1974;Li 1985;Liu 2006). According to textual sources, the two deities first appeared in Chinese mythologies compiled during the Warring States period, although remaining independent from each other. 6 In the third century source Huainanzi, the two were mentioned for the first time in the same passage, but there is no particular description of their relationship (Liu 1989 are two main theories concerning the origin of the two deities' combination. Th e fi rst argues that the two deities did not appear as a couple until the Tang Dynasty. A large number of the supposed depictions of the couple with intertwined snake tails during the Han Dynasty are thus not Fuxi and Nüwa, but merely an anthropomorphic representation of yin and yang. Th e second theory pushed the union of the pair back to the Warring States period of the third century BCE, according to passages that mention Fuxi and his wife Nühuang 女皇 (Nüwa) recorded in the Zidanku silk manuscript from a Chu 楚 tomb.
Regarding the current debate on the identifi cation of the two deities, I propose three additional perspectives. Th e fi rst relies on epigraphical sources while the other two are based on the modes of depicting the sun and moon, as concentrated in this research. Th e most reliable evidence for iconographic identifi cation actually entails inscriptions. Currently, all of the three Fuxi and Nüwa images bearing epigraphical references to the two deities are dated to the Eastern Han.
Th ey were found respectively on a stone sarcophagus from Guitoushan 鬼頭 山 at Jianyang 簡陽, Sichuan (Fig. 19), on a pictorial panel from the Wu Liang Shrine 武梁祠 at Jiaxiang 嘉祥, Shandong (Fig. 1), and on the ceiling of a tomb from Jingbian 靖邊, Shaanxi (   Second, a thorough survey of the depiction of the sun and moon in connection to Fuxi and Nüwa in the Luoyang area indicates that previous scholarship is problematic in terms of distinguishing the imagery of Fuxi and Nüwa from that of Changyi and Xihe. Previous scholarship proposed an exclusive identifi cation of the paired deities in the Bu Qianqiu tomb (Fig. 3), Qianjingtou tomb (Fig. 14,  15), and most of the Eastern Han tombs as Fuxi and Nüwa, while the pair in the Xincun tomb ( Fig. 16) and the Daobei shiyouzhan tomb (Fig. 17, 18) were identifi ed as Changyi and Xihe merely because of the distinctive ways how the sun and moon were depicted (Huang 1996). If based on the four modes identifi ed in current research, the supposed Fuxi and Nüwa refers to the fi rst mode while Changyi and Xihe to the second. However, this absolute distinction contradicts the fact that the second mode was also applied in other Luoyang murals that were identifi ed as representations of Fuxi and Nüwa and dated to a period similar to the Xincun tomb and the Daobei shiyouzhan tomb. In addition, the identifi cation in previous studies did not interpret the chronological sequence of the two modes. Why was the pair of Changyi and Xihe depicted later than Fuxi and Nüwa?
Th ird, previous identifi cations ignore an element that is essential for an iconographic study: the two deities depicted in murals of the Western Han Qianjingtou tomb are both males, in terms of their plain dresses, bold foreheads and the same hairstyle (Fig. 14, 15), while in the Luoyang Han tomb paintings an ordinary female fi gure typically wears headdresses and features a hairstyle that symmetrically separates the bangs into two parts. Thus the current identification of the pair in the Western Han Qianjingtou tomb became problematic, because it is never in doubt that Nüwa is a female goddess. The same problem also appears in the Eastern Han Xincun tomb (Fig. 16), which depicts both the figures wearing an official hat that is only seen on males. Without more evidence for making any further interpretations, definitive answers to the identification issue are perhaps still beyond our reach. However, the notable gender differences discussed above should not be ignored in future research. At the very least, the current evidence suggests that there were two pairs of deities, one pair of a male and a female, while the other of two males, both incorporated the sun and moon in their imagery at the same time.

The Second Mode and its Celestial World: Interpreting Regional Differences in the Depiction of Fuxi and Nüwa during the Eastern Han Dynasty
In the Luoyang area during the Eastern Han Dynasty, it became a standard way to depict a pair of deities in the second mode, which has the sun and moon held upwards by the deities. This mode was also widely applied in other burial centres, including Nanyang (Fig. 8), and the Southwest region (Fig. 2), but not in Shandong/Jiangsu. In the Southwest region, Fuxi and Nüwa are widely depicted on stone sarcophagi, while in Nanyang it is the pictorial stones and bricks that are employed as the primary media. Stone sarcophagi and shrines appeared in China during the period from the second century BCE to the early third century CE in two regions, the Shandong/Jiangsu region on the East Coast and the Southwest region, as an outcome of the transformative wave of the ritual and burial traditions after Emperor Wu's 漢武帝 reformation. During the early stage, images were engraved in thick lines with simple motifs and patterns. Later, more diverse subject matters developed ( Jiang 2001;Wu 2012).
In Shandong/Jiangsu, Fuxi and Nüwa in most cases hold a square and compass respectively (Fig. 1). In the Southwest region, Fuxi and Nüwa are primarily depicted in two ways: the first has them hold the sun and moon (Fig. 2), and the second they hold the square and compass in addition to the sun and moon.
The first type appears earlier and flourishes in a broader area than the second. It could thus be interpreted that the motif of the square and compass was a later addition to the local tradition of representing Fuxi and Nüwa. The possible source is the Shandong/Jiangsu area, where the square and compass are the dominant motifs employed in the imagery of Fuxi and Nüwa (Fig. 1). The concepts of the square and compass could be associated with the natural forms of circle and square. In traditional Chinese cosmology the earth was square and the heavens round, and thus Fuxi holds a set square to draw the former, and Nüwa a compass to draw the circle of the Earth (Whitfield and Sims-Williams 2004, 329). Some scholars propose that these symbols were used to represent cosmic order, a link between heaven and earth, and a favourite environment for the deceased (Lewis 1999, 204).
In Nanyang, the couple sometimes holds the sun and moon (Fig. 8), but in most cases both of them hold lingzhi (Fig. 7). Since cases from the Southwest region are dated relatively later than those from Shandong/Jiangsu and Nanyang, it is possible that the tradition of depicting the pair of the sun and moon as well as that of the square and compass upheld by Fuxi and Nüwa in the Southwest area is a synthesis of influences from multiple areas, including Luoyang, Shandong/ Jiangsu and Nanyang.
How should we perceive the different regional traditions and reconstruct their connections? One angle is to analyse the different cultural information conveyed in pictorial and compositional schemes in each region. No matter whether it is the pair of Fuxi and Nüwa, or Changyi and Xihe, the paired deities with snake-like bodies found in Han tombs from the Luoyang area were interpreted as celestial figures that constitute a heavenly realm. In contrast, the arrangement of the paired deities as part of the celestial world is not prominent in the Shandong and Nanyang areas. The depiction from the Wu Liang shrine in Shandong is located on the second panel of the wall in the second room (Fig. 1). Among Nanyang representations of Fuxi and Nüwa, most are located in the middle part of the vertical slab that supports the structure of stone sarcophagi. The couple is usually arranged above or below door attendants, hunting scenes, or auspicious animals, and sometimes repeatedly appear on one sarcophagus (Fig. 7). Another distinction is the way how the tails of the two deities are arranged. Luoyang tombs tend to have the two separated from each other, while in Shandong/Jiangsu and Nanyang most examples have their tails intertwined. Among Nanyang examples, the couple's tails are intertwined, specially together with the image of Xuanwu 玄武, when they were located on the same stone slab (Fig. 7), unless they are separated symmetrically to two door-slabs (Figs. 10). A similar pattern appears in Shandong/Jiangsu area as well (Figs. 1, 9). In brief, a comparison of the location of the paired deities in the Luoyang, Shandong and Nanyang areas reveals two distinctive groups: Luoyang tombs depict the paired deities in a celestial realm together with the sun and moon, while in the Shandong and Nanyang areas the sun and moon are not essential motifs to the imagery of Fuxi and Nüwa, since the couple is not always located in the celestial realm, and there is also the relative popularity of other motifs, including lingzhi, the square and compass.

The Third Mode: Incorporating the Shandong and Shaanxi Traditions of Depicting the Square and Compass
As briefly mentioned above, the third mode, which has the sun and the moon embraced by Fuxi and Nüwa respectively, already appeared during the Han Dynasty in Shandong/Jiangsu (Fig. 9), Nanyang (Fig. 10) and Shaanxi (Fig. 11), but never became the dominant mode. When it comes to the Wei-Jin period, the third mode began to replace the second as the most popular one. The majority of Wei-Jin tombs were discovered near the major cities of Dunhuang 敦煌, Jiuquan 酒 泉, Jiayuguan 嘉峪關, and Zhangye 張掖. The motifs of Fuxi and Nüwa became more popular in Wei-Jin tombs in comparison to the Han period, but their locations and styles show notable new features. While the Han tombs have the pair depicted on ceilings or upper walls in Luoyang and Shandong/Jiangsu, on the rear end or sides on sarcophagi in the southwest region, and door slabs in Nanyang, the majority of Wei-Jin tombs depict the pair on the inner side of the timber coffin cover (Fig. 12) or pictorial bricks on walls and ceilings (Fig. 5). One theory considers the origin of depicting the pair on coffin covers as a simplification of the practice of covering the coffin lid with Jingming 旌銘 (banner) practiced since the pre-Qin period and after (Liu 2006, 147-48).
Among the surviving examples found on coffin covers, the pair is arranged in two basic types: the first type horizontally locates Fuxi and Nüwa on two ends (Fig.  12), and the second depicts the two vertically facing each other (Fig. 4) (Kong and Hou 2006). It is noticeable that for the first type, the overall design of Fuxi and Nüwa recalls the design on ceilings and upper walls in Han tombs from the Luoyang area. An examination of the historical context of Hexi during the Wei-Jin era provides a connection between the two regions: it was from the Western Han period on that a mass migration along with cultural transmission from the Central Plain to the Hexi Corridor took place. However, the Han tradition of applying the first and the second modes to depict the sun and moon was not inherited by these Wei-Jin burials in the horizontal type. The majority applied the third mode of depicting the sun and moon, which has them embraced by Fuxi and Nüwa respectively (Fig. 12). Tombs in the second type, which arrange the two deities on coffin cover vertically, began to employ the fourth mode, which has the sun arranged above the couple with the moon below (Fig. 4). To sum up, it is firstly at the Wei-Jin Hexi Corridor that the fourth mode came into view, while the third mode became predominant.
One possible answer to the appearance of the third mode at Hexi is the movement of immigrants from the Shandong and Shaanxi areas. The Eastern Han case from Shandong (Fig. 9) and that from Shaanxi (Fig. 11) are distinctive from the one from Nanyang (Fig. 10), as the latter tradition never depicts the square and compass as attributes of the two deities, while the former two areas have the pair of attributes always in together with the sun and moon (Kong and Hou 2006). In Wei-Jin pictorial bricks and coffi n paintings, the sun and moon are always in combination with the pair of the square and compass. To push this discovery further, the Shandong tradition exerts a more explicit infl uence on the Wei-Jin tomb art, since they both depict the two deities with dragon-like bodies, as well as similar ratios regarding the size of the sun and moon and the deities' bodies.

From Nanyang to the Southwest: the Confl uence of the Fuxi and Nüwa Imagery and the Formation of the Sun God and Moon Goddess
Besides being depicted in association with the imagery of Fuxi and Nüwa, the sun and moon have already been widely represented in a variegated range of pictorial contexts. An examination of the visual tradition of depicting the two celestial bodies during the Han and Wei-Jin period reveals an idiosyncratic phenomenon in the Southwest: the appearance of the anthropomorphic rendering of the sun and moon as a pair (Fig. 13, 21, 22, 23). A further inquiry indicates that the formation of the sun and moon in anthropomorphic representation in the Southwest incorporated two visual traditions: that of Fuxi and Nüwa in local tradition, since the sun and moon appear in anthropomorphic form with a rendering of their heads and faces almost identical to that of Fuxi and Nüwa, and that of the sun and moon in Nanyang, where we see the prototype of the Southwest composition for locating the sun and moon as part of a fl ying fi gure's body ( Fig. 24 and 25).    The No. 3 sarcophagus from Guitoushan 鬼頭山, Jianyang 簡陽, discussed above, and which depicts Fuxi and Nüwa with inscriptions (Fig. 19), has its right and left sides carved. Its left side shows two flying figures with human-faces but bird-like bodies (Fig. 13). The left deity has its torso formed in the shape of the sun and the right deity in the shape of the moon. Surviving inscriptions between the two figures reveal that they are Ri 日 and Yue 月. Similar depictions of the sun and the moon have been found on the two other stone sarcophagi from Guitoushan (Fig. 21), as well as on a number of others from the Southwest, such as the Eastern Han tomb at the Temple of Zhaojue 昭覺寺 in Chengdu (Fig. 22), and the brick tomb from Xindu 新都, Xinfan 新繁 (Fig. 23). All of these examples depict the moon and sun as part of the bodies of figures that have human faces with bird-like bodies. In addition, they appear with explicit gender differences: the sun god features a mountain-shaped crown and the moon goddess has a feather-like headdress. The Xinfan case (Fig. 23) depicts a bird inside the orb-shaped body of the sun and a toad in that of the moon. The Guitoushan case (Fig. 21) follows the same manner, although rendered relatively roughly. The Zhaojue case (Fig.  22) merely adorns the sun god with a bird, and also varies from the other cases in terms of the difference in size between the sun and moon.
It is interesting that this anthropomorphic representation of the sun and moon is not applied in any other sites, but only in the Southwest. Even more notable is that their facial features and headdresses are treated exactly the same as those of Fuxi and Nüwa: the mountain-shaped crown for the male, while a feather-like headdress for the female. One may argue that a similar treatment of the paired deities is also identifiable in the case of Dongwanggong (King Father of the East) and Xiwangmu (Queen Mother of the West). However, the Dongwanggong was not seen in the southwest during the Han period. Furthermore, the sun and moon appear in a pair since the beginning, while Dongwanggong was a later creation for making a couple with Xiwangmu, the long-existing deity that has a specific significance in Chinese mythology and already had a long history of transformation by the Eastern Han, when Dongwanggong was created (Wu 1989, 108-41;Gong 1998, 345-77). Thus the tradition of depicting Fuxi and Nüwa is more likely the source for the formation of the sun and moon in an anthropomorphic couple.
To examine the current argument, I further explored the tradition of depicting the sun and moon in other areas during the Han Dynasty, and found that the Nanyang area shares a similar composition with the Southwest, which renders the sun and moon as part of the bodies of flying figures. The majority of the Nanyang examples show the sun depicted as embraced by a bird, while the moon appears just like an ordinary disc within which is a toad or hare (Fig. 24). But it is notable that the moon disc with a toad was gradually transformed into part of a flying bird, in symmetry with the sun-bird. The bird is very likely the crow that is conventionally depicted within the sun. The way that the bird is depicted is no different from the three-legged crow represented within the sun disc from the Han Dynasty. Now if we turn to the tradition of representing the sun and moon in anthropomorphic form in the Southwest (Figs. 13,21,22,23), the composition and iconography are no different from the Nanyang tradition (Fig. 25), except for their human faces. In other words, the practice of depicting the sun and moon embraced or as part of the bodies of a bird already became popular in the early Eastern Han Dynasty in Nanyang. As it turns to the later Eastern Han, the Nanyang tradition, together with the already established tradition that depicts Fuxi and Nüwa in a gender-discernible pair, provided sources for the creation of the anthropomorphic representation of the sun and moon in the Southwest. Nevertheless, it is difficult to reach any absolute conclusions with regard to the motivation for the creation of the anthropomorphic sun and moon, just like the long-debating issue regarding the creation of the anthropomorphic Buddha images. This requires further research on the overall historical, cultural, and visual landscape of the Southwest during the Han Dynasty.

Eastern Han Nanyang: Fuxi and Nüwa as Representatives of Fertility
As indicated above, the sun and moon were never the dominant attributes in the Nanyang depiction of Fuxi and Nüwa, but developed more extensively as celestial orbs that usually appear amidst constellation diagrams. Derivative but necessary to address, through the examination of the essential features of the Fuxi and Nüwa imagery created in different regions during the Han Dynasty, it is explicit that the tradition of the Nanyang area is much more distinctive and diverse than that of other regions. In addition to the preference for lingzhi in Nanyang, another trait is the incorporation of Xuanwu (Dark Warrior) in the imagery of Fuxi and Nüwa. Xuanwu is one of the four mythological animals that are typically termed Sishen 四神 (four deities), each guarding one of the four cosmic directions and four seasons (He 1998, 183-88;Wang 1995). They are Qinglong 青龍 (blue dragon), Baihu 白虎 (white tiger), Zhuque 朱雀 (red bird), and Xuanwu 玄武 (Dark Warrior). Xuanwu is the guardian of the north, the utmost point of the yin. On the pictorial stone slab from Xinye 新野 Lihu 禮湖 at Nanyang, Fuxi and Nüwa are located facing each other with their bodies intertwined over a Xuanwu at the bottom. It is identifiable through the inscription above it, and its appearance in the conventional rendering of a Xuanwu as a tortoise encircled by a snake (Fig. 7). Xinye Lihu is not the first case of representing Xuanwu together with Fuxi and Nüwa in Nanyang, but the combination is not standardised. On another pillar from the same tomb, the paired deities are represented in a way that is same but without Xuanwu.
It is clear that Xuanwu's natural connection to the north and the winter does not constitute a satisfactory answer here. The location of the configuration in the Xinye Lihu tomb of Nanyang has no directional reference, but instead as one of a group of motifs on one stone slab. The current identification tends to explain the appearance of Xuanwu as a counterpart of a Giant figure which forms another tradition of the genesis mythology and fertility (Wang 1990). Even without referring to the Giant figure, it is also legitimate to perceive the connection between Xuanwu and fertility according to Xuanwu's trait of representing yin. In addition, both visual and textual traditions reveal that Xuanwu has not been fixed as one of the Sishen until the late Eastern Han. A more conservative interpretation of the combination of Xuanwu with Fuxi and Nüwa is the snake part of Xuanwu's iconography. In extant depictions of Xuanwu in combination with Fuxi and Nüwa, the snake part of the Xuanwu is at the same time the lower body of the two deities. Thus it is this resemblance makes it possible to have Xuanwu visually connected with other snake-or dragon-like creatures.

The Development of the Fourth Mode in the Hexi Corridor Since the Wei-Jin Era
Finally, the fourth mode depicts the sun above Fuxi and Nüwa with the moon below ( Fig. 4, 6), naturally in a vertical setting. Although most surviving materials showing this mode are silk or hemp paintings and banners found in Turfan burials dated to the Tang Dynasty from the sixth to seventh centuries (Fig. 6), the prototype of the fourth mode already appeared in the Wei-Jin era, from the third to fifth centuries, on the coffin covers in Jiayuguan burials (Fig. 4).
Considering the focus of this article is the period between Han and Wei-Jin, I will not delve into the discussion regarding the formation nor the function of the fourth mode in Tang funerary paintings (Stein 1928;Xinjiang Weiwuer zizhiqu bowuguan 1972;Uyeno 1974;Whitfield 1985;Chen 2001). But it is worth presenting several discoveries based on a preliminary comparison of the fourth mode between the Wei-Jin example and the successive Tang paintings.
First is the distinction in the overall setting of the painting between Wei-Jin Jiayuguan and Tang Turfan. In the Wei-Jin case (Fig. 4), the two deities are surrounded by mountain ranges, which on two sides have peaks facing outwards, while a group of Tang banners fill the surrounding space with scattered constellation diagrams (Fig. 6). The Tang banners' interest in celestial symbols also shows in the way that the sun and moon discs were rendered abstractly: the sun appears with radiating beams inside and moon in the crescent shape. Furthermore, some even have the orbs surrounded by a ring of stars.
Second is the replacement of the traditional rendering of the two deities' headdresses with a new mode in Tang banners. The Wei-Jin example inherited the convention of rendering Fuxi with a mountain-shaped hat and Nüwa with a crown, while in all of the Tang paintings Fuxi began to feature an ordinary official cap, while Nüwa a plain knot. Both the figures appeared more human-like, in comparison to the divine treatment of their predecessors from the Han to Wei-Jin. In addition, they dress in short pleated tunics.
The third discovery is regarding the origin of the vertical arrangement of the sun above with the moon below. One may argue that this type is done to deal with the limitations of the chamber or the silk banner's elongated rectangular shape, although I believe that it is not sufficient to attribute the motivation to spatial concerns alone. Here I come up with a hypothesis that the arrangement of the sun and moon on the ends of a vertical space in the fourth mode might be related to the tradition of representing the sun god and wind goddess at the two ends of the central strip on the ceiling in Buddhist cave-temples at Kizil, which is on the northern branch of the Silk Road. But a concrete conclusion requires a further examination of cave-temple arts before making any further arguments. This hypothesis is also based on the importance of celestial symbols for both the Turfan silk paintings and the central strip paintings in Buddhist cave-temples (Ma 1996;Zhu 2003). In brief, the Tang silk paintings show a clear departure from the traditional depiction of Fuxi and Nüwa, however they have certainly been influenced by the Wei-Jin conventions due to the same way in which they render the sun and moon in the fourth mode.

Conclusion
Instead of proposing an integrated narrative of the evolutionary history of the Fuxi and Nüwa imagery, this research starts with a pre-iconographic study of the visual materials that we have at hand. Putting the primary emphasis on the description and classification of the Fuxi and Nüwa imagery in terms of how the sun and moon are incorporated, I identified four primary modes and discussed their historical and regional features. Further examination and analysis of each mode contributed to the current field by providing new perspectives for readdressing some issues that remain underexplored, and bringing back to the field several pictorial traditions that should not be neglected in the study of the Fuxi and Nüwa worship.
This study challenges the over-absolute identification of the earliest representation of Fuxi and Nüwa in a pair, and that of Changyi and Xihe, another set of paired deities recorded to be in close relation to the celestial world, in Western Han mural tombs from the Luoyang area. The relatively late date of the Eastern Han, when the earliest epigraphical texts referring to Fuxi and Nüwa and other textual and historical sources were dated to, leave open the question as to when Fuxi and Nüwa were formed into a pair, and when they were represented together with the sun and moon, and this thus requires further research. Instead of identifying the paired deities with snake-bodies as Fuxi and Nüwa, or Changyi and Xihe, based on undemonstrated distinctions in visual or textual traditions, the present research suggests a shift of focus to the recognisable distinctions in visual details. These differences include the shift from depicting the sun and moon in the first mode to the second upon the beginning of the Eastern Han, and the masculine appearances of both the deities depicted in the Western Han Qianjingtou tomb. Second, regional variations significantly portray the development of each mode. While the first mode was only seen in the Luoyang area, the second mode prevails in the entire northern areas during the Han Dynasty, and kept on flourishing during the Wei-Jin era. The third mode appeared in the Eastern Han, but did not flourish until the Wei-Jin era in Hexi. Although its origin cannot be absolutely ascertained, its noticeable co-existence with the pair of the compass and square alludes to its close connection to the tradition of Shandong and Shaanxi. The fourth mode was not seen beyond the territory of the Hexi Corridor, from its appearance in Wei-Jin era and its later flourishing in funerary banners during the Tang Dynasty. Further examinations reveal more complicated interactions between different regions and exchanges of motifs with other imagery. The local tradition of depicting Fuxi and Nüwa, together with that of the depiction of the sun and moon in Nanyang, has been incorporated with the formation of the sun and moon in the anthropomorphic representations seen in the southwest.
Finally, a thematic research is defined by information retrieved from materials, rather than the use of a later-created terminology. Instead of making absolute identifications, it is more significant to organise the surviving materials through detailed examinations of each visual element. In addition, an iconographic study of images without the consideration of their original contexts will muddy the waters with its over-imposed set of classifications.