More than 900 ancient tombs likely dating back to the Silla Dynasty have been discovered in Cheongdo, North Gyeongsang Province.

The North Gyeongsang Province Institute of Cultural Properties said Thursday it has dug up about 940 tombs believed to have been built during the Silla Dynasty at a reservoir construction site in Cheongdo.

The institute said many of the tombs, which are believed to have been built between the late fourth century and the early sixth century, are stone-lined jar coffin tombs.

It expects the excavation to help researchers study the formation and development of a local political system, citing historical records pointing to the existence of an independent political force in the area.