Ask a question: Is the population growth in Jiangnan really slow in the first and middle period of Qing Dynasty?

As for immigration, you just need to remember that immigration is always two-way, with a larger population and greater advantages.

The yield of three-season rice in the south is doomed, and the population of China can only expand from south to north forever.

Of course, in fact, Mongolians are also from the south, because human beings can't stand the weather in the north from the beginning. They all walk along the equator.

Minnan in the south of the Yangtze River seems to be, like, Hakka immigrants. People in this place have some characteristics. History seems to be like a massacre in southern Fujian, which led to a sparse population. Now people there have only one surname.

Anyway, Minnan is a special case outside the laws of the universe.