Archaeologists have unearthed 18 ancient tombs from different periods in North China's Shanxi province.

The excavation was conducted by the provincial institute of archaeological research from February to May 2017 in Taigu county, where a high-speed railway line section is about to be built.

Three of the tombs were confirmed to date back 800 years to dynasties of the Jin (1115-1234) or Yuan (1271-1368), and the others were built later, Wang Jun, an associate researcher with the institute, said Sunday.

More than 80 pieces of buried articles, such as porcelain bowls and oil lamps, were also excavated, said Wang, leader of the excavation team.

One of the tombs was a long trapezoid tomb with 11 recesses in the tomb wall, and was believed to be built in the Jin or Yuan Dynasty.

He said at least 15 skeletons, male and female, were placed in porcelain coffins after cremation in the recesses in the 6-meter-long tomb.

"Cremation was rare in ancient Chinese funerals, and the tomb was possibly connected to Buddhists," Wang said, adding that the tombs had provided significant materials for studying the funeral characteristics at that time.

Chinese people traditionally believe the body must be kept intact and buried in the soil for the soul to rest in peace. However, cremation has been popular among Buddhist monks for centuries.