What kind of social phenomenon is the migration of population to the south and the reform of Emperor Xiaowen in the Northern Wei Dynasty?

It is a social phenomenon of the great integration of northern nationalities.

First, the great integration of the northern nationalities:

After the end of the Eastern Han Dynasty, the Xiongnu, Xianbei, Biandi, Qiang and other ethnic minorities who moved to the Central Plains continuously lived with the Han nationality for about 400 years, learning from each other in production and learning from each other's strengths. By the end of the Northern Dynasty, the differences between Hu and Han gradually disappeared, and the great national integration was realized. At that time, the study of Chinese culture by ethnic minorities was essentially promoting their feudalism. Feudalization is conducive to national integration. The realization of national integration prepared conditions for the unification and prosperity of Sui and Tang Dynasties.

Second, the essence of the great integration of northern nationalities:

The essence of intermarriage, complementary production and learning Chinese culture between ethnic minorities and Han nationality is to publicize their feudalism.

Third, ethnic integration and assimilation:

Ethnic integration refers to the mutual influence of several ethnic groups on the basis of the same economic thought, which is the result of close contact and exchange between many ethnic groups in economy, politics, culture and living habits.

National assimilation refers to the phenomenon that a nation (or part of it) loses its own national characteristics and becomes another nation. There are two forms of national assimilation in history, one is forced assimilation and the other is natural assimilation.

In ancient China, the process of ethnic integration generally refers to the process of feudalization of ethnic minorities, or the process of ethnic minorities moving from living on weeds to settled agriculture. Therefore, ethnic integration is a historical progress, an important condition for the unification of multi-ethnic countries due to division, and a process of the gradual formation of the Chinese nation.

The Three Kingdoms, the Jin Dynasty and the Southern and Northern Dynasties are a climax of national integration and a major feature of this historical period, which is manifested in the following aspects:

1. Ethnic migration in two directions: the five lakes move inward and northerners move south.

2. Three stages of ethnic integration: at the end of the Eastern Han Dynasty and the beginning of the Western Jin Dynasty, ethnic integration appeared along the Great Wall after Wuhu moved in; During the Sixteen Countries Period of the Eastern Jin Dynasty, the pace of integration accelerated. During the Northern Wei Dynasty, ethnic integration reached its climax.

3. Four ways of integration: ethnic migration, friendly exchange, joint struggle and minority regime reform.