In the ruins of the White City
Tongwancheng 统万城( called Baichengzi 白城子, "White City" by the locals) lies 48 km north of Jingbian 靖边县 (Provinz Shaanxi, near the border to Inner Mongolia). It was built in 418 AD by the Xiongnu leader Helian Popo in his state Xia 夏 (407-431). During Tang and Song it fell victim to the desertification of the region.
The site was researched and described by a Qing-official in 1845. After 1956, it was "discovered" once more by Chinese archaeologists.