How to understand the disadvantages and advantages of the historical phenomenon of northerners moving south?

The significance of northerners moving south: 1. Develop a large area of land in the south, so that agriculture in South China can develop rapidly; 2. A large number of craftsmen brought advanced technology from the Central Plains; 3. Compared with the Central Plains, the relatively stable environment and the rapid development of agriculture, industry and commerce have gradually shifted the economic center of China from the Central Plains to the south. After the Tang Anshi Rebellion broke out, a large number of northern people moved south to escape the war. Since then, due to the separatist regime of the buffer region, the peasant war in the late Tang Dynasty, the warlord scuffle and the evasion of heavy taxes, the northern people moved southward until the end of the Five Dynasties and Ten Kingdoms, forming the second wave of the northern people moving southward in the history of China. Immigrants have moved south all over the country, and the Jiangnan area around Zhejiang, Shanghai, Jiangsu and Anhui is one of the main immigrant areas. Immigrants, especially scholars going south, added new factors to the society of Tang and Song Dynasties and had an important impact on the economic and cultural development of Jiangnan.