Huai'an, formerly Huaiyin, is a prefecture-level city in central Jiangsu Province in Eastern China. As of 2020, the built-up area of its 3 central urban districts had 2,544,767 inhabitants and the prefecture-level city as a whole had 4,556,230 inhabitants, down from 4.8 million in 2010. Long an important regional center, Huai'an lies on and is named for the Huai River, the historical boundary between Northern and Southern Chinese culture.