About this sound Chongming County, is the only county in the provincial-level municipality of Shanghai in China. The county consists of three low-lying inhabited alluvial islands at the mouth of the Yangtze north of the Shanghai peninsula: Chongming, Changxing, and Hengsha. Following its massive expansion in the 20th century, Chongming is now the 2nd-largest island administered by the People's Republic of China and the 3rd-largest in Greater China, after Taiwan and Hainan.