As a result of the interaction between historical reasons and geographical factors, in ancient times, people may have said the same word when they originated, and then some of our ancestors went to the north, and some came to the south for survival, so some sounds changed from generation to generation, and because of the influence of environmental geographical location, many nouns didn't exist before, so they gave different names to the same thing according to their respective accents. Because ancient communication was relatively closed, it was handed down from generation to generation in this small circle, and then some people moved to other places around them in order to survive. The same evolution process formed the dialect of China. If you can find out for yourself, the dialects in the more advanced areas are very similar, which is what I said before.