Yiyang (simplified Chinese: 益阳; traditional Chinese: 益陽; pinyin: Yìyáng) is a prefecture-level city at the Zi River in Hunan province, China. According to the 2010 Census, Yiyang has a population of 4,313,084 inhabitants residing in an area of 12,144 km². The last census was in 2000 when it was recorded there were 4,309,143 inhabitants.