The Dachen Islands, Tachen Islands or Tachens are a group of islands off the coast of Taizhou, Zhejiang, China, in the East China Sea. They are administered by the Jiaojiang District of Taizhou. Before the First Taiwan Strait Crisis in 1955, the islands were administered by the Republic of China (ROC).

Zhejiang is an eastern coastal province of the People's Republic of China. Its capital and largest city is Hangzhou, and other notable cities include Ningbo and Wenzhou. Zhejiang is bordered by Jiangsu and Shanghai to the north, Anhui to the northwest, Jiangxi to the west and Fujian to the south. To the east is the East China Sea, beyond which lies the Ryukyu Islands. The population of Zhejiang stands at 64.6 million, the 8th largest in China. It has been called "the backbone of China" because it is a major driving force in the Chinese economy and being the birthplace of several notable people, including the Chinese Nationalist leader Chiang Kai-shek and entrepreneur Jack Ma. Zhejiang consists of 90 counties.