What are the reasons for the changes in China's ancient social structure?

The reasons for the changes of social structure in ancient China are: the development of natural economy.

Social structure: broadly speaking, it can refer to various structural conditions in economic, political, social and other fields. In a narrow sense, it mainly refers to the social stratum structure in sociology.

After the mid-Ming Dynasty, due to the invasion of foreign capital, China's natural economy began to collapse, which led to the germination of capitalist economy. The economic base determines the superstructure.