The skulls were found in what appears to have been a mass grave at the Shimao Ruins, the site of a neolithic stone city in the northern province of Shaanxi.

The women’s bodies were not present, the official news agency Xinhua said, adding that archaeologists concluded that the skulls were “likely to be related to the construction of the city wall” in “ancient religious activities or foundation ceremonies” before construction began.

There may have been an outbreak of mass violence or ethnic conflict in the region at the time since “ancient people were prone to use their enemies or captives as sacrifices”, it added.

The discovery is not the first instance of researchers unearthing remains related to human sacrifice in early China. Kings and emperors were regularly buried along with their servants and concubines, who were sometimes killed first — and on other occasions buried alive.