Communism first emerged in glimpses through socialism in the nineteenth-century. It was inspired by Karl Marx. In Marxist theory, communism served as the last stage in historical development consisting of a full development in areas regarding collective living and social equality.
Communism reached its peak during the 1970's. By then, around a third of the world was run under a communist government. The countries that endorsed communism the most were the USSR and China. Communism had also made its way to Eastern Europe, Vietnam, North Korea, Cuba, and among other places.
Europe was the first host to the Cold War. The Soviet Union was really concerned over the security and control over Eastern Europe. There was a big wish from American and British governments for open societies that were linked to the capitalist movements. Much like the previous two World Wars, alliances were formed. The two alliances were the NATO and Warsaw Pact. The American sphere of influence was a lot more voluntary than the Soviet one, they imposed it.
The spread of communism into Asia caused conflicts between the Asian countries. This led to North Korea invading South Korea in 1950. The war lasted three years and it involved interference from the United States and China. The war ended with a Korea that was divided more than ever.
The Cold War also sparked the Vietnam War. The United States was heavily involved in Vietnam and tried to keep communism out in the 1960's. By 1975, the Vietnamese communists successfully unified the country.
In Afghanistan, a Marxist took control in 1978 but had the majority of the population. The Soviet Union's military came in but had little success. By 1989, the Soviet Union, under immense public pressure, withdrew from there and that led to the imminent fall of communism in Afghanistan.
In Cuba, Fidel Castro had come into power in 1959. The United States became hostile as a result of the nationalization of US assets. As Castro's reign progressed, he began to align himself with the USSR.