During the Three Kingdoms and the Jin Dynasty, a large number of northerners crossed the river one after another. What is the connection with the rapid economic development in Jiangnan?

Politically, the ruler's move to Jiangnan will make Jiangnan the center of political activities and strengthen the management of internal affairs and justice. Economically, the economic exchanges between the north and the south have been strengthened, and the economic development focus of the rulers has also moved south; In terms of science, education and culture, northern immigrants brought advanced Chinese culture from the Central Plains to the south of the Yangtze River, and strengthened ideological and cultural exchanges and scientific and technological innovation; The strengthening of ethnic relations has promoted the great integration of the Chinese nation. These are all reasons. PS: I am a liberal arts student. I may write my answers, but I wrote them all myself.