[Photo provided to China Daily]

Ruins of rows of houses in the area indicate that people lived quite comfortable lives, with separate bedrooms and kitchens, according to the excavations.

Colorful pottery and jade articles have also been found, said Wang Fen, head of the Jiaojia excavation team.

The area was believed to be the political, economic and cultural center of northern Shandong 5,000 years ago. Ruins of ditches and clay embankments were also found.

The Jiaojia ruins fill a cultural gap 4,500 to 5,000 years ago in the lower reaches of the Yellow River, according to Wang Yongbo of the Shandong Provincial Institute of Archaeology.

Archaeologists found obvious damage to the head and leg bones of some of the bodies and to pottery and jade articles in six large tombs. The damage may have been caused not long after the burials and may be due to power struggles among high-ranking people.

Li Boqian, an archaeologist with Peking University, said the excavations showed Jiaojia in a transition phase, but proved the existence of ancient states 5,000 years ago in the basin of the lower Yellow River.

The size of the Jiaojia site has been quadrupled to 1 square kilometer. Currently, only 2,000 square meters have been excavated.

"Further study and excavation of the site is of great value to our understanding of the origin of culture in East China," said Zhou Xiaobo, deputy head of the Shandong Bureau of Cultural Heritage.

Xinhua