On 21 April, Communist forces crossed the Yangtze River. On 23 April and they captured the KMT's capital, Nanjing. The KMT government retreated to Canton (Guangzhou) until October 15, Chongqing until November 25, and then Chengdu before retreating to Taiwan on December 10. By late 1949, the People's Liberation Army was pursuing remnants of KMT forces southwards in southern China, and only Tibet was left. On October 1, 1949, Mao Zedong proclaimed the People's Republic of China with its capital at Beiping, which was renamed Beijing. Chiang Kai-shek and approximately 2 million Nationalist Chinese retreated from mainland China to the island of Taiwan. This officially started the communist rule in China.