Reason:
The river here refers to the Yellow River. Because of the different geographical locations, there is a vast radiation area and material distribution center behind the west, and the ocean behind the east, and sulfhydryl bulk materials have to cross the river, so the development is not good. So Hexi is relatively rich and Hedong is relatively backward. No, it's the address location.
Extended data:
We often say that "thirty years in Hedong, thirty years in Hexi" is also related to this.
When the river flows through the bend, the water quality point moves in a curve, resulting in centrifugal force. Under the action of centrifugal force, the surface water tends to the concave shore, and the bottom water flows from the concave shore to the convex shore under pressure, forming a curved circulation. Under the action of curved circulation, concave banks are eroded and convex banks are accumulated, and rivers become more and more curved.
Due to the long-term erosion of the concave bank, "cutting and bending to get straight" will occur, forming an oxbow lake. The west coast of the past has become the east coast of today.
Nowadays, "thirty years in Hedong, thirty years in Hexi" is used to describe the rise and fall of personnel, which is changeable.