Why did the population of China skyrocket in the early Qing Dynasty?

The main reason is that sweet potatoes and corn were introduced into China. These two plants are very easy to grow and can be planted in a large area on barren land. Land that could not be cultivated before is now useful. In addition, it has high yield and good starch content (anti-hunger) and can feed many people.

The only thing that limited the population growth in ancient China was the lack of food. Once there is a shortage of food, parents will drown their babies, which controls the population growth. During the Qing Dynasty, there was no large-scale war in the hinterland of China (Wu Sangui was too early to count), so there was no war to reduce the population. The large-scale planting of corn and sweet potato has solved the food problem, and the result is a rapid population growth.

Another point is that Kangxi said that he would never increase taxes. Later, Yongzheng Tanding went to Mu and abolished the poll tax. It turns out that people don't have children or report for less tax. Now the poll tax is unnecessary, the natural population has increased, and there is no need to hide a large number of people, so it has appeared.

In the past, the main food of China people was rice, wheat and millet, so the population has been hovering between 30 million and 60 million. But this is official data. In ancient times, a large number of tax evaders would hide themselves, so the official population was generally small. It seems that some scholars believe that the population of China has exceeded 1 100 million in the Song Dynasty.