China is a multinational country with the Han nationality as the main part, and has a vast territory, a long history, a large population and complicated dialects. However, complicated bifurcation of dialects formed some independent languages in the long course of Chinese history. Unified characters and written language were the key factors.

That is because that Chinese characters and written language are unified. Though people in different places pronounce Chinese characters differently in their dialects, they can have the same understanding of the Chinese characters and the written language. Therefore, Chinese characters and the Chinese written language that takes Chinese characters as the writing signs can surmount the difference in dialects to become the common communication tool for the whole people.

Though a written language usually takes a certain dialect as its basis, it is still a bit different from the spoken language. Since there were only a comparatively small number of Chinese characters in ancient times, people employed characters with the same pronunciation to solve the inconsistency between the real language and Chinese characters and meet the need of communication. That was a quite interesting phenomenon.