History of Guyuan
Guyuan, is a prefecture-level city in the Ningxia Hui Autonomous Region of the People’s Republic of China. It occupies the southernmost section of the region, bordering Gansu province to the east, south, and due west. This is also the site of Mount Sumeru Grottoes (须弥山), which is among the ten most famous grottoes in China. The area was declared by the United Nations to be, “one of China’s most impoverished regions and one of the world’s least habitable areas for human beings.”
Source From: https://en.wikipedia.org/wiki/Guyuan