Mostly, I believe it's because of economic prosperity. In China, the East Coast has a lot of industry and is a major point for exports, making it wealthier than the inland regions. Just look at cities like Shanghai or Guangzhou, their buildings show how prosperous they are. This has resulted in more people moving to these cities for work, and fewer people remaining in the rural areas. The demographic differences are quite clear because of this.
主要是因为经济繁荣。在中国,东海岸有很多工业,并且是主要的出口地点,这使得它比内陆地区更富裕。看看上海或广州这样的城市就知道了;他们的建筑展示了它们有多繁荣。这导致更多人搬到这些城市工作,而农村地区的人口则减少。由于这个原因,人口分布的差异非常明显。