"Migration has been a vital social change throughout all ages. In the ancient societies, migrations usually took place as a result of natural disasters, wars, or the need to develop the border regions.
We would put the dynasties of Qin and Han aside for the time being and start from the Northern and Southern Dynasties. During the social upheaval that lasted for well over a century, more than a million people moved down south, which was 1/7 of the number originally present in the North. The migration has set the foundation for shifting the economic and population center from northern to southern China.
