Fourth-tier cities. Most of the fourth-tier cities are medium-sized cities with relatively ordinary city size, level of economic and social development, and transportation construction. Line cities are mostly predominantly prefecture-level cities, but also include the provincial capitals of individual provinces and autonomous regions, capitals, autonomous regions. According to Baidu Encyclopedia, the latest data for the list of fourth-tier cities in 2021, including Changde City, Chenzhou City, Shaoyang City, Yongzhou City, Huaihua City, Loudi City, Xiangtan City, Yiyang City and other cities. Therefore, Yiyang City is a fourth-tier city.