XI'AN, Dec. 2 -- Archaeologists in northwest China's Shaanxi Province said they had excavated over 80 skulls in the ruins of the largest neolithic Chinese city ever discovered.

The skulls were found in groups and their limb bones could not be retrieved elsewhere at the Shimao Ruins in Shenmu County, Yulin City, said Sun Zhouyong, deputy head of the Shaanxi Provincial Institute of Archaeology, on Sunday.

Two groups of skulls were firstly found in two pits, with 24 of the grisly finds in each, in front of the east gate of the city ruin while others were later uncovered along the eastern city wall, Sun said.

Archaeologists deduced that these skulls are likely to be related to the construction of the city wall, suggesting that ancient religious activities or foundation ceremonies were launched before construction of the neolithic city began.

Sun said anthropologists identified most of the skulls as belonging to young women, which suggested the outbreak of mass violence or ethnic conflict in the region since ancient people were prone to use their enemies or captives as sacrifices.

These skulls will serve as important materials for research on the religious thinking, construction concepts and cultural activities of people living along the Yellow River Basin over 4,000 years ago, according to Sun.

The Shimao Ruins were first found in 1976 in the form of a small town, and archaeological authorities identified the ruins as the largest of their kind from neolithic times in 2012 after measuring the exact size of the ancient stone city.

Archaeologists said the city was built about 4,300 years ago and was abandoned roughly 300 years later during the Xia Dynasty (2100-1600 BC), the first dynasty in China to be described in ancient historical chronicles.