Some of the paintings have been damaged by mud and silt while others have peeled off or cracked due to the rains. The paintings carved on individual rocks were more seriously damaged, Xinhua news agency reported.
Most boundaries were destroyed due to flood, damaging cliff paintings, said Hu Zhiping, deputy director of Helan Mountain Cliff Painting Administration in Yinchuan City, capital of the region.
The extent of the damage was still being investigated. Protection measures will hopefully minimise the losses, Hu said.
Helan mountain has around 20,000 cliff paintings carved by the nomads that once lived in northern China. The paintings are scattered over several hundred kilometres.
The paintings depict herding, hunting, sacrificial rites and life episodes of the people who lived 3,000 to 10,000 years ago.
