Mounds claim their rightful place in history

Among the Heishuicheng literature, researchers also discovered Tiansheng Gaijiu Xinding Lyuling, or "The new laws in the years of Tiansheng (1149-1169) modified from the old one".

It is the longest, most detailed and best preserved code of laws, that is known of Xixia. It includes nearly 200,000 Tangut scripts.

"This is the oldest surviving comprehensive legal code left by a non-Han ethnic group in Chinese history," Shi says.

He says the code was compiled on the basis of laws of Tang and Song dynasties, and similar physical evidences of legal codes from other Chinese dynasties of its time were rare.

The code also records Xixia exchanged with not only surrounding regimes but also Central and even West Asia through tribute, market fairs, and mutual trades along the Silk Road.

And findings on Xixia Imperial Tombs may resonate with the recordings.

On the outer wall of Mausoleum No 3, arc-shaped corner towers may tell its possible inspiration from similar battlements in West Asia while most such structures in ancient China were square-shaped.