Why are the economic activities of the population of West and East China not the same?

The east of China has historically been the center of the formation and development of the entire country. The population density on the coast and along the canal connecting the Yellow River and the Yangtze is still one of the largest on the planet. And in a small area in the east, as well as in the Pearl River delta in the south of the country, more than six hundred million people are concentrated. It is clear that due to such a concentration of the population, the area here is extremely inhabited, developed, finances and production are concentrated here. Western China is much less developed.