Interested people can search Dr. AARON Li's thesis.
There have been numerous invasions by Hu people in history, but not all Han people fled to the south of the Yangtze River. Hu's invasion did not occupy the whole north at the same time. They mainly fight and plunder, and all the people who provide rations for farming are Han Chinese.
Moreover, the population of the invading Hu people is far less than that of the Han people in the north.
During the Five Chaos Period, many Hu people came to the Central Plains, accounting for half at most. That is, half Han people and half conference semifinals in the north. Hu people are cruel and kill Han people. When Ran Min led the Han Jedi to fight back, Wuhu suffered heavy casualties, and the Hu family, the Jie family, which was the most cruel to the Han people, was basically extinct.
There is also a daily war between Wuhu and Wuhu, and there are fewer and fewer losers. Please remember that the Hu people are soldiers and the Han people are farmers. The death rate of soldiers is much higher than that of farmers. Therefore, when the Northern Wei Dynasty unified the North, except Xianbei, few other Hu people killed each other, so in the Northern Wei Dynasty, there were mainly two branches in the North, Xianbei and Han.
Xianbei is an illiterate people. He is also a farmer and a soldier in China. The queens of Xianbei are almost all Han nationality, and the population is smaller than that of Han nationality. With the promotion of the upper class, Xianbei quickly became Chinese. However, after the coup, a small tribe of the Bo nationality, the Wang family in the Yuan Dynasty and the Luoyang nobles in Xianbei were almost slaughtered. Of course, Jules' life didn't end well. Xianbei people are completely integrated into the Han nationality.
5. The Han regime that existed in the north during the China chaos: Liang Qian, Beiyan, Wei Ran, early Beiliang, Xishu, etc.
Under the regimes of Jurchen, Tangut and Qidan itself, the Han people were in the majority. Their demise was related to the Mongolian massacre. The brutality of Mongolia is outrageous. In history, Mongols slaughtered countless cities, wiped out hundreds of people, turned fertile land in the north into pastures, and 80% of the population in the north disappeared. How many Jurchen, Tangut and Qidan are left? There are also many nationalities in the direction of Mongolia's western expedition.