The Eastern Bloc, also known as the Communist Bloc, the Socialist Bloc, and the Soviet Bloc, was the coalition of communist states of Central and Eastern Europe, East Asia, Southeast Asia, Africa, and Latin America under the power of the Soviet Union that existed during the Cold War (1947–1991). These states followed the ideology of Marxism–Leninism, in opposition to the capitalist Western Bloc. The Eastern Bloc was often called the "Second World", whereas the term "First World" referred to the Western Bloc and "Third World" referred to the non-aligned countries that were mainly in Africa, Asia, and Latin America but notably also included former pre-1948 Soviet ally Yugoslavia, which was located in Europe.
In Western Europe, the term Eastern Bloc generally referred to the USSR and Central and Eastern European countries in the Comecon (East Germany, Poland, Czechoslovakia, Hungary, Romania, Bulgaria, and Albania). In Asia, the Eastern Bloc comprised Mongolia, Vietnam, Laos, Kampuchea, North Korea, Syria and China. In the Americas, the countries aligned with the Soviet Union included Cuba from 1961 and for limited periods Nicaragua and Grenada.
The term Eastern Bloc was often used interchangeably with the term Second World. This broadest usage of the term would include not only Maoist China and Cambodia, but also short-lived Soviet satellites such as the Second East Turkestan Republic (1944–1949), the People's Republic of Azerbaijan (1945–1946) and the Republic of Mahabad (1946), as well as the Marxist–Leninist states straddling the Second and Third Worlds before the end of the Cold War: the People's Democratic Republic of Yemen (from 1967), the People's Republic of the Congo (from 1969), the People's Republic of Benin, the People's Republic of Angola and People's Republic of Mozambique from 1975, the People's Revolutionary Government of Grenada from 1979 to 1983, the Derg/People's Democratic Republic of Ethiopia from 1974, and the Somali Democratic Republic from 1969 until the Ogaden War in 1977.