Cliff paintings in northern China that date back to prehistoric times face severe damage from natural erosion and human destruction, according to a Chinese archaeological expert.
About 80 percent of ancient cliff or rock paintings in Ningxia, Inner Mongolia, Xinjiang and Qinghai have sustained damage through the forces of erosion and human activity, combined with a lack of protection, said expert Zhou Xinghua.
"Cracks, falling pieces and collapses have made the previously clear pictures difficult to identify and some have even completely disappeared," said Zhou,
The northwestern region boasts rich remains of such paintings with the most famous sites at the Helan Mountain and Damaidi.
The eastern part of the Helan Mountain has 2,318 cliff paintings in an area of seven square kilometers.