Thirty years east of the river and thirty years west of the river mean that it was on the east bank of the Yellow River 31 years ago and on the west bank of the Yellow River 31 years later. This sentence is often used to describe the ups and downs of the world, and the wind and water turn around.

Thirty years east of the river, thirty years west of the river "is a folk proverb, which originated from the natural phenomenon that the Yellow River often changed its course in history. In the past, the Yellow River was not fixed, and it often changed its course (it happened countless times in history). A place used to be in the east of the river, but in a few years, due to the diversion of the Yellow River, this place will become in the west of the river. This sentence is a metaphor for the rise and fall of personnel, which is changeable and sometimes changes to the opposite side, which is unpredictable.

Related historical allusions:

Guo Ziyi's grandson can only beg after losing all his property. Once, he begged to Hexi Zhuang and went to visit the wet nurse. I asked a lot of people and said I didn't know. When it was getting dark, a farmer came. When he inquired, he found that the farmer was the son of his wet nurse. When he went to other people's homes, he saw grain stores and horses and cattle.

He asked the farmer, "Why do you have to work by yourself when your family is so rich?" The son of the wet nurse said, "No matter how big the property is, it will be empty. When my mother was alive, she led us to start a business, and this family business came into being. It's fun to be thrifty and keep a house! " Guo Sun was ashamed after hearing this. The master did not forget the old feelings, so he let Guo Sun take care of the accounts at home, but he knew nothing about accounting. The master could not help sighing, "It's true that in thirty years, Hedong enjoyed endless splendor and preciousness, and in forty years, Hexi was dependent on others."