Jìyīn

Jiyin was a county name associated with Caozhou in the plains of southwestern Shandong. The district's history was repeatedly shaped by the Yellow River and its floods. In 1168 flooding destroyed the seats of both the prefecture and Jiyin county, and the authorities moved north to the old site of Chengshi, near present-day Heze. Later changes in administration and river courses altered the relationship between the old names and the settlements that inherited them.

In the early Ming, another flood prompted Caozhou's seat to move south to Panshi in 1369. The prefecture was reduced to Cao county two years later, but in 1445 Caozhou was re-established at the old Chengshi site north of the river. The separate names of Cao county and Caozhou remained in use for different places. In 1735, under the Qing, Caozhou was raised to the rank of a prefecture and a new county named Heze was established at its seat. These successive moves show how control of a fertile but flood-prone plain depended on changing waterways as well as administrative decisions.