The feudal system in China meant that poor people were treated like slaves and many took up that class. This system lasted for almost 300 years under the Qing dynasty until it fell in 1911.
Other countries such as Britain seized ports in order to trade and encouraged free thinking and democracy.
Democracy! Free choice!
Mao Zedong, the leader of the communist party, said that these countries were trying to "train intelectuals who will... dupe the people."
The communist party had been in civil war with the nationalists since the end of WWII but that ended when Mao Zedong announce the People's Republic of China (PRC) on October 1st of 1949. The communists controlled most of China's mainland by the end of the year and most ocuntries recognized it as a legitimate government.