It can be said that the Central Plains at that time basically included most of the northern regions. The north has become a battleground for countless aspirants, which will inevitably bring war. At that time, the south was deserted and had no war value. As the saying goes, the soldiers and horses have not moved their food and grass first. At that time, there was no war potential in the south, so the south was relatively stable.
Especially because of the influence of the Five Chaos, the north fell into the sea of Wang Yang at war, and a large number of people chose to move south, because the south at that time had not been baptized by war. After the Northern Song Dynasty, the economy of the south gradually surpassed that of the north. Especially after the continuous defeat of the Song Dynasty War, Han people began to move to the south in large numbers, which inevitably led to the economic development of the south.
In particular, the natural conditions in the north are getting worse and worse, and there are many local ethnic minorities, which often invade on a large scale, so it is difficult for the Han nationality to survive in the north. The stability in the south has attracted countless people to move south. For people at that time, stability was more important than anything else. The war in the north can be said to be frequent. Basically, most ancient wars took place in the north, so people began to move south in desperation.
Moreover, at that time, nomadic people in the north often harassed the border, and it was basically difficult to have peace in the north. Whether in the Han Dynasty or the Tang Dynasty, the disputes in the north never stopped. So at that time, it was hard to see that some people chose to move north, and basically they chose to move south.