Archaeologists have found 13 tombs, estimated to be between 1,800 and 2,700 years old, in Bomi county of Tibet region.
The tombs were discovered by construction workers during a road building project in Nyingchi in 2016, Xinhua news agency quoted the Regional Institute of Cultural Relics as saying.
Two relatively complete human skeletons were found in two tombs, while human bones were also discovered in other graves, said Shaka Wangdu, associate researcher with the institute.
Archaeologists found that the tombs appeared to follow a known burial custom, which is still seen in parts of Qundo.
According to the custom, the bones are exhumed and reburied after the body has decayed.
Objects including eight complete examples of pottery, a millstone, three bronze arrowheads and iron residue were also found.
"The tombs will help research into Tibetan funeral customs and human development in eastern Tibet in a period without written records," said Shaka Wangdu.