Remains uncovered from tombs in the Tibet autonomous region's eastern Bomi county have been verified as being up to 2,700 years old, according to a researcher.

The 13 tombs were excavated at the end of last year in Chudo township, about 600 kilometers from Lhasa, the regional capital. The site lies at an altitude of 2,900 meters.

The exposed area of the 13 tombs covers up to 700 square meters, with each tomb measuring 80 centimeters long and 50 cm wide, according to the Institute of Cultural Relics Protection in Tibet.

"Tests on human skeletons from three selected graves showed that the oldest grave has a 2,400 - to 2,700-year history, while the most recent is 1,800 years old," said Shargan Wangdu, an associate researcher at the institute.

The findings are of great value for studies on Tibet's funeral culture and human development in eastern Tibet during a period for which there are no written records, he said.

Based on two relatively complete human skeletons found in two graves, researchers found the tombs used a known ancient funeral method, which is still use in parts of Chudo now, whereby after a corpse has been buried and decayed, the bones are collected and buried again at a second funeral.

In addition, objects such as pottery, stoneware and metalwork were also found in the tombs, including eight pieces of pottery, a millstone, three bronze arrows and scattered iron pieces.

The newly discovered ancient tombs have provided "precious material" for researchers to understand funeral customs from 2,000 years ago, Shargan Wangdu said.

The tombs were found in the second half of last year when locals built a road in Bomi, with timely measures ensuring the tombs were excavated before being damaged.