The British trade opium with China, but when addictions get to be a problem, they up a fight and tried to get rid of the opium. Britain won the war.
China and Japan fought over a section of China's land. Japan won and claimed more territory for their empire.
Chinese citizens wanted the empress and dynastic system gone, so they fought.
The United States formed a treaty and it stated that all trade was equal and open between all countries and China
The ideas of communism reached China and the Communist Party formed.
The trek to northwest China by Communists who were being hunted and removed by the Nationalists.
Mao's Communist party and ideas build up enough power to fight the Nationalists. The win the fight, causing Nationalists to flee and Communism to start to control China.
This is when Mao started really changing China into a Communist country. It started all equal payment and treatment, and made huge farming plantations to grow food on, which miserably failed.
China was becoming a bit too extreme for the Soviet Union, so they cut ties with them.
Communist China began to strictly enforce Communist ideas, and all intellectuals, landlords, or people with high position and money were publically humiliated and denounced. Kids would join the Red Guard and enforce the Communist ideas.
President Nixon went to China to strengthen the bonds between the two countries.
When Chairman Mao dies, the Cultural Revolution and the extreme Communist ideas come to a close.
It began as a rally for change in political power and which government system should be used, and turned into a massacre of unarmed civilians when the government attacked to stop it from continuing.