In 1911, the long-smoldering revolution against the rule of the Manchus broke out. The revolutionaries, with Sun as provisional president, set up in Nanjing a national assembly, representing provinces mostly in the south. The emperor formally gave up his throne in early 1912, and Yuan Shih-k'ai assumed control of a republican government in Beijing. To unify China, Sun resigned his position, allowing Yuan to become the republic's first president. Yuan, however, began to suppress the revolutionaries, establishing himself as dictator.

Meanwhile, Outer Mongolia declared itself independent in 1911; Tibet followed in 1913. China refused to recognize their claims to independence, but lacked forces to reconquer them.

After the death of Yuan in 1916, China broke up into local regimes headed by military officers called warlords. The national government in Beijing was dominated by a succession of warlords. In 1917, the revolutionaries' Kuomintang, or Nationalist party, established its headquarters in Guangzhou. There it founded a constitutional government headed by Sun in opposition to the one in Beijing. In 1923 the Kuomintang began to receive aid from the Soviet Union and to accept Chinese Communists as members.

Upon the death of Sun in 1925, General Chiang Kai-shek became head of the Kuomintang government. In 1926, he launched the Northern Expedition, long planned by Sun to unify China. The Kuomintang army, allied with a Communist army and five friendly warlord armies, drove north and defeated various warlord forces, securing central China.

In 1927 the drive was halted when Chiang expelled the Communists and forced Soviet advisers to leave China. Many Communists were killed or jailed, but the main Communist forces withdrew into the mountains of Jiangxi province in southeast China. Chiang's reorganized Nationalist government was established at Nanjing, and in 1928 the Northern Expedition was resumed. Beijing was captured and renamed Peiping, but the Nationalist government was not completely in control. Warfare continued both against rebellious warlords and against the Communists.

Meanwhile, traditional customs, such as the wearing of the queue by men and the binding of women's feet, were being abandoned under the influence of the West.