During the Southern and Northern Dynasties, northern minorities went south to the Yellow River basin. Why?

The first is natural factors. The climate in the north is too bad and the environment is bad. Relatively speaking, the climate of the Yellow River Basin is warm and humid, which is suitable for survival.

Secondly, the agricultural civilization in the Yellow River Basin developed earlier, with abundant resources and social wealth.

These two reasons, I think, are the main reasons why ancient northern nomads in China committed crimes in the south.

Finally, personally, this reason is the most important. Historically, every time the northern minorities occupied the Yellow River basin, whether it was dynasty division, civil strife, natural and man-made disasters or peasant uprising, it was the time when the strength of the Han Dynasty in the Central Plains declined. In the Western Jin Dynasty, because of the rebellion of the Eight Kings, the country split and the dynasty collapsed. It led the northern minorities to go south to the Yellow River basin, resulting in the "Five Chaos China".