The partnership between China and the World Bank began on December 27, 1945 when it joined the organization. After the Communist victory in 1949 in the Chinese Civil War, the Chinese Communist Party proclaimed the People's Republic of China (PRC) on the mainland while the Republic of China (ROC) government retreated to the island of Taiwan, formerly a Japanese colony it acquired in 1945 after the end of hostiles in World War II. Both governments claimed to be the sole legitimate of China leaving Taiwan's political status unclear.