European countries maintained colonies from the 1500s up through the 20th century.
In 1947, India gained independence from Great Britain. France maintained control of countries in Southeast Asia.
As the economic and military strength of the “great powers” (as they are sometimes referred to) declined, they found it increasingly difficult to retain control over their far flung colonial empire. In many cases, local people sought to rebel against their colonial masters.
As World War II came to an end, the Soviet Union sought to promote communism, while the United States sought to promote democracy. These two emerging great powers entered into a “cold war” in which they attempted to gain influence with people in various countries. In many cases, the Soviet Union supported people groups who were rebelling against their colonial masters. To counter efforts by the Soviet Union to extend its influence, the United States adopted a strategy known as “containment” and began to support groups who had been friendly with their former colonial rulers.
A good example of this is Vietnam. Formerly a French colony, the Soviet Union supported North Vietnam and insurgents in the south called the Viet Cong. At first, the French tried to support the South Vietnamese government. When they pulled out, the United States stepped in an attempt to prevent the expansion of communism.
At the same time, a struggle over whether the world would follow a Soviet style central planning model or an American free market capitalist model of economic policy was also going on. The Soviet Union supported the growth of Communism in China, and supported the rise of Mao Zedong, the Communist Leader. The United States and Great Britain supported Chiang Kai-Shek, whom they felt would pursue free market economic policies. Eventually, the Communists prevailed and Chiang Kai-Shek fled to the island of Formosa and established what was known as “Free China.” Today, the name of the country is Taiwan. Mainland China became known as Red China.
Today, most all of the colonies that were once ruled by the Great Powers have attained independence. Additionally, with the collapse of the Soviet Union, the Cold War has come to an end.
A great book to read on this general subject is Paul Kennedy’s book: The Rise and Fall of the Great Powers: Economic Change and Military Conflict from 1500 to 2000.