Changzhou is a prefecture-level city in southern Jiangsu, China. It was previously known as Yanling, Lanling, and Jinling. Located on the southern bank of the Yangtze River, Changzhou borders the provincial capital of Nanjing to the west, Zhenjiang to the northwest, Wuxi to the east, and the province of Zhejiang to the south. The population of the Changzhou Municipality was 5,278,121 at the 2020 census. The city is the birthplace of Zhou Youguang who created the pinyin romanization system.