Archaeologists have discovered the remains of a 4,000-year-old city that they say might have been the capital of China's first slave kingdom.

Archaeologists from Beijing University and the Henan Provincial Research Institute of Archeology discovered the city ruins at the Wangchenggang site, near the city of Dengfeng in Central China's Henan Province, after working for three years from 2002 to 2004.

Archaeologists said the ruins might belong to Yangcheng, the capital of King Yu, founder of the Xia Dynasty (about 2100 B.C.- 1600 B.C.).

"There are enough reasons for the city ruins to be the site of King Yu's capital, whether from the location recorded in history or from the scale of the city," said Prof. Liu Xu, head of the excavation team.

Archaeologists have unearthed a moat, a city wall, sacrificial pits with human skeletons, long hollow pieces of jade with rectangular sides and white pottery, in a 3,000-sqm area.

"These discoveries suggest that the city may have been a major settlement for people in Central China some 4,000 years ago," said Fang Yanming, with the Henan Provincial Research Institute of Archeology.

Archaeologists excavated a small city to the northeast of the newly discovered bigger city at the Wangchenggang site in 1977. Relics including fragments of bronzeware, inscribed characters and a dozen pits containing human skeletons had been found.

The ruins of the small city, covering just a few thousand square meters, were then thought to have been the capital of King Yu.

However, many refused to accept the small city ruins as the capital because of its small scale.

"The discovery of the larger city site throws new light on the identification of King Yu's capital," Fang said.

The two cities were constructed in the same manner, although the smaller city was built a little earlier than the bigger one.

Some archaeologists said the smaller city might have been used for sacrifices. Others thought the bigger city might have been built after the small city was devastated by floods. Yu, a legendary hero and the founder of China's first slave society, made his name by fighting floods some 4,000 years ago.

Editor: Catherine