​Beijing, July 26 (IANS) Archaeologists have confirmed traces of ancient humans, dating back to over 10,000 years, at an altitude of 4,000 metres in China's Qinghai-Tibet plateau.

Hou Guangliang of Qinghai Normal University confirmed that the prehistoric ash layer discovered in 2013 is a residue of human activity, Xinhua news agency reported.

Dozens of stone tools were found at the same site, showing signs of civilisation in the plateau, making it the oldest evidence of human activity at over 4,000 metres.

The discovery is of great significance to research on how ancient humans coped in extreme environments, Hou said.

The plateau has an average altitude of 4,000 metres where winter temperatures can drop to -40 degrees Celsius.​