Were there any large-scale immigrants in the Ming Dynasty? Why?

The migration of Sophora japonica in Hongdong in Ming Dynasty was the largest, longest and widest organized and planned migration in the history of China. After the war at the end of Yuan Dynasty, after more than 20 years, Zhu Yuanzhang unified the world. However, at this time, the mountains and rivers were devastated and devastated. Shandong, Henan and Hebei are mostly uninhabited areas. In order to restore agricultural production, develop the economy, balance the population, make the world peaceful and consolidate the rule of the Ming Dynasty, Zhu Yuanzhang adopted an immigration policy during the Hongwu period of the Ming Dynasty, and moved in according to the proportion of "four families stay one, six families stay two, and eight families stay three". According to the general history of China Ming, recuperation and land reclamation, Zhu Yuanzhang began to emigrate from 1307 to solve the contradiction between labor shortage and land shortage in narrow rural areas. He ordered more than 4,000 landless peasants from Song, Jia, Hu and Hangzhou in Jiangsu to go (in Huaiyuan, Dingyuan, Fengyang and Jiashan in Anhui), and 400,000 people from the south of the Yangtze River to Fengyang, and moved the landless peasants from Shanxi Ze (Jincheng, Shanxi) and Shandong (Changzhi, Shanxi) to Hebei, Shandong and Henan. All immigrants who cultivate the land are paid by the court, and cattle and seeds are tax-free for three years. The great immigrants in Ming Dynasty experienced three emperors: Hongwu, Wen Jian and Yongle. It lasted for 50 years. Covering several provinces in the Central Plains and East China, covering more than half of China. Immigrants of the Ming Dynasty are unprecedented in the history of China and very rare in the history of the world.