Nearly 4,000 cliff tombs have been discovered in the city of Shangluo, Northwest China's Shaanxi province.

"We have found nearly 4,000 cliff tombs in over 700 locations in all the districts and counties of the city," said Wang Changfu of the city's museum.

Since 2003, the Shaanxi Provincial Institute of Archaeology and the Shangluo Museum started a field research project investigating the tombs in the city. So far, a total of 3,936 cliff tombs in 722 locations have been found.

Buried objects including glazed pottery kettles, tripods, pots and bronze basins were excavated at a tomb located in Shangnan county. Some of the tombs were found to be built in the Eastern Han Dynasty (25 AD-220 AD).

It was an ancient custom to dig a tomb chamber on a cliff in the southern part of the province as well as in Southwest China. Excavating these tombs will help promote the research on the cultural evolution and funeral customs in the region, Wang said.