Archeologists in northwest China's Ningxia Hui Autonomous Region said Tuesday they have found ruins of seven prehistoric residences near famous cliff paintings.

"These are the earliest remains of the forefathers of the Chinese people, and they possibly created those marvelous works," said Zhou Xinghua, a noted expert on cliff paintings and a former curator at a regional museum.

The ruins were found on the slopes of Beishan Mountain in Damaidi, a 450-square-km area where more than 20,000 rare cliff paintings have been identified since the late 1980s.

"Each residence was encircled by a fence made of rocks," said Zhou, adding that the fences were between 0.4 and 1.1 meters tall.

Zhou and his colleagues are yet to identify how old the ruins are. "But they provide evidence the Damaidi area was inhabited in ancient times."

The rock carvings in Damaidi are believed to be a treasure trove of information on the social, religious, artistic and folk customs of prehistoric humans beings.

Paleographers say the cliff paintings may take the historical evidence of Chinese characters' existence much further back, from the current 4,500 years to 30,000 years.