Mountain of relics

Guo's team has unveiled the layout of the city, including its road network, waterways and temples. Unearthed coins from Tang (618-907) and Song (960-1279) dynasties speak volumes for its booming business while tile decorations indicate social status and influence from Persia to Central Asia.

"The city was constructed uninterruptedly for 150 years under the Tang Dynasty. Small-scale adjustments in layout happened in the periods that followed. The city played a pivotal role until the Yuan Dynasty (1271-1368)," Guo says.

In 702, Tang empress Wu Zetian ordered the setting up of the Beiting Protectorate there to govern the north of Tianshan. In the following centuries, it saw many dynasts come and go. Nonetheless, from Tubo and Qocho regimes to Khitans and Mongols, ambitions to uphold cultural exchange and ensure good business along the Silk Road were shared.

For instance, although Buddhism was widely in practice under the Qocho regime, Guo's team unearthed a Christian relic-the cross-near the ruins of a Buddhist temple.

"The urban system centering the Beiting ruins demonstrates inclusiveness, mutual learning and cooperation. They help us understand how a shared community of a Chinese nation was formed," Guo says.