Archaeologists have unearthed 21 tombs dating back to the Western Han Dynasty (206 BC-AD 24) in the central Chinese city of Changsha, Hunan province, which are possibly subordinate tombs of a royal mausoleum, according to the municipal institute of archaeology.

Zhou Baodong, head of the excavation project, says that the tombs are all earth pits and can be divided into two types — tombs with passageways and those without.

Zhou adds that many of the graves were found side by side, which may be joint tombs for couples or family members.

Notably, archaeologists found a unique tomb in the cluster. As per speculation, it may be a two-tiered structure, which is rare to see in Hunan province.

"If our speculation proves true, it will provide important clues for studying the development and distribution of double-decked tombs during the Han Dynasty (206 BC-AD 220)," Zhou says.

A total of 234 burial items, mostly pottery artifacts, were found in the tombs.

Given the proximity and similar ages of the burials, archaeologists say that they are likely to be subordinate tombs for an ancient royal mausoleum.

The new findings can provide basic information for studying the burial system in present-day Changsha during the Western Han Dynasty, Zhou says.