China had been a republic from 1912. It was no longer ruled by emperors. The country was politically unstable, and the government had little control. The National People's Party, known as Guomindang, sometimes written as 'Kuomintang', grew more powerful and began to solve some of these problems. In 1928, the party's leader, Chiang Kai-shek, captured Beijing. He set up a new government with the support of the businessmen and landowners.
Between 1927 and 1934, Chiang waged five 'encirclement campaigns' against a rival group, China's communists. They were led by Mao Zedong (sometimes written as 'Mao Tse-tung'). In 1934, Mao and 100,000 communists fled to Yenan in north-west China on 'the Long March'; it was a horrific 6,000-mile march. As they marched, they fought their way past ten opposing armies. Only 20,000 arrived alive in Yenan, but Mao was able to create a small communist state and build up his power.
After the Second World War, the communists waged a guerrilla war against Chiang Kai-shek's government. The Guomindang government was corrupt, and did nothing to improve the life of the peasants. Mao's communists were popular with the peasants, promising land reforms. In 1949, Chiang Kai-shek fled to the island of Taiwan.
Mao Zedong took control of a country of 600 million peasants, that was ruined by war and on the brink of mass-starvation. Not everyone agreed with his policies while he was in power, and they are still the subject of much debate.