Despite the national unification of 1928, the KMT government in Nanking had incomplete control over the country at large, where former warlords remained in semi-independent rule. Within the KMT party, factional disunity was serious. Chiang Kaishek's power was dependent on the army and conservative forces like businessmen and landlords. In other words, his foundation of rule was built on sheer force, not on an ideology. Because of these factors, the internal reforms attempted by the Nanking government generally failed to solve the serious socio-economic problems in the extensive countryside. In the eyes of the people, the KMT became more and more corrupt and reactionary. It seemed another warlord power.
The CCP, on the other hand, experimented with different policies of expansion after its break with the KMT. First, it attempted violent uprisings, but all ended in failure. The attempted promotion of labour movements in the cities was equally unsuccessful, and the advocacy of continued alliance with the middle-class like the KMT was evidently unrealistic and hopeless. Only Mao Tse-tung's policy of organizing the peasants and establishing Communist territorial bases systematically was workable. In so doing Mao was not following Communist doctrines strictly; he was changing them to suit China's particular conditions.
Through effective organization and propaganda, every village that the Communists controlled was turned into a fighting base: A guerrilla military strategy was employed. The purpose was to systematically build up and enlarge strong territorial bases in a prolonged armed struggle with the KMT.
Such realistic policies were successful at first. However, after 1931, a group of Soviet-trained young Communists challenged Mao's leadership, and many of his policies were reversed. Violent land confiscation was practised, and positional warfare against the KMT was adopted. This explained why social support for the CCP decreased and the Kiangsi base was consequently lost. In late 1934, breaking through the KMT's siege, the Communists began the Long March (1934-35) north-westward to Yenan in Northern Shensi.
In 1936, Chiang Kai-shek tried to destroy the Communists in Yenan once and for all. However, there occurred the Sian Incident in late 1936, when Chiang was kidnapped by a former warlord and was forced to agree to an alliance with the CCP against Japanese aggression. Thus the Second KMT-CCP Coalition (1936-45). It was born against a background of widespread Chinese demands for internal unity against the Japanese aggressors, and a strong force of Chinese nationalism cleverly made use of by the Communists, who themselves were encouraged to ally with the KMT by Soviet Russia. The effects of the Coalition were the quickening of the outbreak of the Second Sino-Japanese War (1937-45), during which the KMT was weakened but the CCP strengthened.