What are the main reasons for the formation of Chinese dialects?

There are many factors in the formation of dialects, including social, historical and geographical factors, such as long-term small-scale peasant economy, social division, population migration, mountains and rivers and so on. There are also factors that belong to the language itself, such as the imbalance of language development and the conflict and influence between different languages. The formation of dialects is closely related to immigration and racial integration. In fact, all contemporary Chinese dialects have been greatly influenced by the ancient Xia dialect (ancient Huaxia dialect) in the Western Zhou Dynasty, which is why all dialects in China with different phonetics are called Chinese. In fact, the grammatical rules of various Chinese dialects are also highly similar. There are also some Han areas in China, mainly in the south, which are less influenced by the modern Central Plains language, so that the face of ancient Chinese is preserved relatively completely. Among them, Min dialect is recognized as an important dialect that retains more phonological features of ancient Chinese.