Modern communism found its political and philosophical roots in nineteenth-century European socialism, inspired by the teachings of Karl Marx. Although most European socialists came to believe that they could achieve their goals peacefully and through the democratic process, those who defined themselves as communists in the twentieth century disdained such reformism and advocated uncompromising revolution as the only possible route to a socialist future. Russia, later called the Soviet Union, was the first country to experience such a revolution. Other movements that later identified or allied with the Soviet Union likewise defined themselves as communist. In Marxist theory, communism also referred to a final stage of historical development when social equality and collective living would be most fully developed, largely without private property. Socialism was an intermediate stage along the way to that final goal.

By the 1970s, almost one-third of the world’s population lived in societies governed by communist regimes. By far the most significant were the Soviet Union, the world’s largest country in size, and China, the world’s largest country in population. But Mongolia had come under communist rule in 1924 as a spillover of the Russian Revolution. Communist regimes came to power in Eastern Europe in the wake of World War II and the extension of the Soviet military presence there. Following Japan’s defeat in World War II, its Korean colony was partitioned, with the northern half coming under Soviet and therefore communist control. In Vietnam, a much more locally based communist movement, under the leadership of Ho Chi Minh, embodied both a socialist vision and Vietnamese nationalism as it battled Japanese, French, and later American invaders and established communist control first in the northern half of the country and after 1975 throughout the whole country. The victory of the Vietnamese communists spilled over into neighboring Laos and Cambodia, where communist parties took power in the mid-1970s. In Latin America, Fidel Castro led a revolutionary nationalist movement against a repressive, American-backed government in Cuba. On coming to power in 1959, Castro moved toward communism and an alliance with the Soviet Union. Finally, a shaky communist regime took power in Afghanistan in 1979, propped up briefly by massive Soviet military support. None of these countries had achieved the kind of advanced industrial capitalism that Karl Marx had viewed as a prerequisite for revolution and socialism. Indeed, in one of history’s strange twists, the communist revolutions of the twentieth century took place in largely agrarian societies. (See Map 21.3, for a global view of the communist world in the 1970s, the period of its greatest extent.)

In addition to those countries where communist governments controlled state power, communist movements took root in still other places, where they exercised various degrees of influence. In the aftermath of World War II, communist parties played important political roles in Greece, France, and Italy. In the 1950s, a small communist party in the United States became the focus of an intense wave of fear and political repression known as McCarthyism. Revolutionary communist movements threatened established governments in the Philippines, Malaysia, Indonesia, Bolivia, Peru, and elsewhere, sometimes provoking brutal crackdowns by those governments. A number of African states in the 1970s proclaimed themselves Marxist for a time and aligned with the Soviet Union in international affairs. All of this was likewise part of global communism.

These differing expressions of communism were linked to one another in various ways. They shared a common ideology derived from European Marxism, although it was substantially modified in many places. That ideology minimized the claims of national loyalty and looked forward to an international revolutionary movement of the lower classes and a worldwide socialist federation. The Russian Revolution of 1917 served as an inspiration and an example to aspiring revolutionaries elsewhere, and the new Soviet Communist Party and government provided them aid and advice. Through an organization called Comintern (Communist International), Soviet authorities also sought to control their policies and actions.

During the cold war decades, the Warsaw Pact brought the Soviet Union and Eastern European communist states together in a military alliance designed to counter the threat from the Western capitalist countries of the NATO alliance. A parallel organization called the Council on Mutual Economic Assistance tied Eastern European economies tightly to the economy of the Soviet Union. A Treaty of Friendship between the Soviet Union and China in 1950 joined the two communist giants in an alliance that caused many in the West to view communism as a unified international movement aimed at their destruction. Nevertheless, rivalry, outright hostility, and on occasion military conflict marked the communist world as much as or more than solidarity and cooperation. Eastern European nations’ resentment of their Soviet overlords boiled over in periodic rebellions, even as the Soviet Union and China came close to war in the late 1960s.

Although the globalization of communism found expression primarily in the second half of the twentieth century, that process began with two quite distinct and different revolutionary upheavals—one in Russia and the other in China—in the first half of the century.