Archaeologists in China have unearthed the skulls of more than 80 young women 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. Scientists believe the women may have been sacrificed more than 4,000 years ago.

According to the official news agency, the women’s bodies were not present, adding that archaeologists concluded that the skulls were “likely to be related to the construction of the city wall in ancient religious activities or a founding ceremony of the city.

At the time there may have been an outbreak of mass violence or ethnic conflict in the region, as ancient people were prone to use their enemies or captives as sacrifices.

The find is not the first related to human sacrifive in early China. It was common for kings and emperors to be buried along with their servants and concubines, who were sometimes killed first – and on other occasions even buried alive.

The Shimao Ruins cover more than four square kilometres and were discovered in 1976. Sun Zhouyong, deputy head of the Shaanxi Provincial Institute of Archaeology, said that part of the skulls “show signs of being hit and burned”.

Archaeologists have also found more than 100 remains of murals as well as large amounts of jade ware at the site of the ancient city, which sits in the Yellow River basin and is believed to date back to 2000 BC.

In 2005 archaeologists at Hongjiang in the central province of Hunan found an altar devoted to human sacrifice as well as the skeleton of one victim. A separate altar was used for sacrificing animals at the 7,000-year-old site, which is believed to be the earliest human sacrificial site ever found in the country.