About 4 200 years or 4 000 years ago

there was a flood period of 200 years in north China for the influence of atmosphere.So the myth of how Dayu controlled the floods also has true links with facts and history.Dayu regarded Yuanzhou as the core of flood-controlling

and the strategy he took was "dredging nine rivers

gathering river Ji and Luo into sea ".The group named Si in the Xia tribe migrated east as Dayu dredging river Ji and Luo

then settled down in the Ji and Luo area after Dayu ascending the throne.It is found that the proof not only includes lot of materials of ancient history

but also the materials of archaeological fieldwork.