The site of Tangchaodun (lit. Tang Dynasty mound) is located in Qitai County, Changji Hui Autonomous Prefecture, Xinjiang Uygur Autonomous Region. The rain and snowmelt at the northern foot of the Tianshan Mountains nourishes an oasis corridor between the Tianshan Mountains and the Gurbantünggüt Desert, about 60 kilometers wide from north to south. Starting from Yiwu [the ancient name of modern Hami City in Xinjiang] and then crossing the Tianshan Mountains, the “new northern route” [a route opened during the Eastern Han Dynasty between 25 and 220 CE] of the Silk Road ran westward through the oasis corridor. The site of Tangchaodun is located along this east-west traffic artery.

From 2018 to 2022, Renmin University of China and the Xinjiang Uygur Autonomous Region Institute of Cultural Relics and Archaeology cooperated to conduct archaeological excavations at the Tangchaodun site. In addition to a large number of unearthed relics, archaeologists also found several architectural remains including the sites of an early Tang courtyard, a Buddhist temple, a Romanesque bath, and a Nestorian church. These discoveries vividly demonstrate the abundance of cultural exchanges between China and the West along the Silk Road.

Pulei County

The east wall of Tangchaodun was built along the course of the Shuimo River. The north, west, and south walls are arranged in a straight line, forming a nearly rectangular site with an area of about 160,000 square meters. The site derived its name from a high platform, 12 meters in length, located in the middle of the city’s north wall.

According to the Yuanhe Junxian Zhi, a geographical work written during the Tang Dynasty (618–907), Pulei County was built in 640. Radiocarbon dating of rammed earth samples drawn from layers of the Tangchaodun city walls shows that the city was first built around 596±42 CE, which corresponds to the date of the establishment of Pulei County in historical records. Another 10th-century geographical treatise, the Taiping Huanyu Ji, or Universal Geography of the Taiping Era (976–983), records that Pulei County was 80 li [a traditional Chinese unit of distance] east of the Tingzhou Prefecture [the Beiting city ruins in Jimsar county, Xinjiang]. The straight-line distance between the site of Tangchaodun and the Beiting city ruins is about 30 kilometers, which is consistent with the record in the Taiping Huanyu Ji. Hence, there is sufficient evidence to conclude that the site of Tangchaodun was in fact the government seat of Pulei County under the jurisdiction of the Tingzhou Prefecture during the Tang Dynasty. Archives and archaeological excavations reveal that Tangchaodun was first built in the Zhenguan era (627–649). Ravaged by wars, this county was gradually abandoned during the reign of Chagatai Khanate in the 14th century.

The Buddhist temple

The ruins of the Buddhist temple are located on a rammed-earth platform in the center of the Tangchaodun site. The ruins of an underground palace at the base of a pagoda were found in the west wing of the temple, which is a square crosssection 1.8 meters deep. To the east of the underground palace is a rectangular Buddhist Hall. There is a rectangular platform est of the Buddhist Hall, with damaged murals on its northern wall connecting it to the wall of the hall. The platform is speculated to be the base of a statue of Buddha.

Based on the location of the temple, its post-excavation layout, and the unearthed murals and small Buddha statues, it is reasonable to assume the presence of a Buddhist temple at the site, with a main hall in the front, a pagoda and an underground palace in the back, as well as cloister-like architectural structures. It may have first been built during the same period as the ancient Pulei County, and used until the reign of Qocho Kingdom [a Uyghur kingdom existed from 866 to the early 13th century].

The Romanesque bath

The Romanesque bath site is located in the northeast of the Tangchaodun site. It consists of a brick main structure flanked by an adobe structure on the east side, a site for a furnace on the north side, and wells for its water supply and drainage on the left and right sides of the furnace section. Located at the center of the bath site, the brick main structural plan is a nearly square, approximately 12 meters long from north to south, and 11.5 meters wide from east to west. The interior of the bath is divided into nine zones by brick walls: the central zone is octagonal, and the layout of the remaining eight zones are symmetrical pairs. There are five exhaust vents on the outer walls of the bathhouse.

The bath is a semi-crypt structure, consisting of upper and lower floors. The lower floor is an underground space used for flues and heat supply. The surface structure, where people bathed, is above ground. Most of the surface structure has collapsed, except for the bathroom wall, about 0.4 meters high with a black and grey coating, which remains in the southwest corner.

The upper floor of the bath is raised above the ground by pillars erected in the underground space. This construction technique is known as “hanging flooring” in the De architectura, written by Marcus Vitruvius Pollio in ancient Rome, in which supporting pillars are used to build the underground heating system of the bath. When in use, the heat and smoke produced by the furnace will spread through the flue among the pillars under the hanging floor, forming “underfloor heating” to maintain the temperature of the bath above the ground.

In functional terms, the bath site can be divided into three zones: the foyer in the east, the operations zone in the north, and the bathing area in the southwest. The doorways in the south and north ends of the foyer likely led to the changing rooms. The operations zone is area where the furnace, water supply and drainage systems are located. The furnace provides hot water for bathing, and the heat generated maintains the temperature of the bath through the underground heating system. Based on its distance from the furnace, the bathing area on the southwest side can be subdivided into the tepidarium (warm room), the caldarium (hot room), and the frigidarium (cold room), etc. Analysis of cultural layers and unearthed relics at the bath site suggests that this bath was first built during the period of Qocho Kingdom.

The bath ruins boast strong Roman styles in layout and construction techniques, while the relics and floral decorations on the wall are indicative of both Central Plain and local cultures. It reflects the interaction and innovation of Chinese and Western construction traditions and techniques along the Silk Road.

The Nestorian Church ruins

The Nestorian Church ruins are located in the north of the Tangchaodun site. Its main building is rectangular in plane, about 32 meters long from east to west and 24 meters wide from north to south.

Rich mural remains have been found at the church site. There are many images of donors found among the murals, whose appearance, in terms of hair accessories and clothing, is quite consistent with images of donors found in other areas of Xinjiang dating to the period of Qocho Kingdom. Several relatively complete facial images, most of whom feature curly hair and plump figures, are similar to figures found in the paintings of the Tang Dynasty. This reflects the inheritance of the Tang culture by the Qocho Uyghur people. The murals dated to the Qocho Kingdom period not only depicted donors and auspicious patterns that are similar to Buddhist art, but also embodied Nestorian elements such as the cross, scepters, palm branches, and inscriptions of Yelikewen in Chinese [Erke'ün, literally, Servants of the Gospel]. This represents the exchange, fusion, and innovation of the Eastern and Western cultures along the Silk Road.

Radiocarbon dating suggests that the Nestorian church was first built during the Tang Dynasty. Its main building may date to the period of Qocho Kingdom. The church was abandoned at the same time as Tangchaodun due to human destruction in the 14th century.

The Nestorian Church, officially the Assyrian Church of the East, is referred to as jingjiao in Chinese documentation after being introduced into China. Currently, only a limited number of Nestorian remains have been found in the world, mainly in Iran, Iraq, Kyrgyzstan, and Uzbekistan.

The archaeological discoveries of the Tangchaodun site have confirmed the historical facts of ethnic integration, religious coexistence, and cultural compatibility from the Tang to the Yuan (1271–1368) dynasties.

Wei Jian is a professor from the School of History and Culture at Minzu University of China; Wu Tong is a Ph. D student from Renmin University of China.