Poland is a state in Central Eastern Europe and is home to approximately 38 million people. The country is the sixth largest member state of the European Union. The capital and biggest city of Poland is Warsaw. Poland is made up of 16 voivodships. The largest river in the country is the Vistula (Polish: Wisła).
Czechoslovakia was a state existing between 1918 and 1992 with changing borders and under changing names and political systems, the former parts of which were absorbed into the present-day states of the Czech Republic, Slovakia and Ukraine (Carpathian Ukraine, already occupied by Hungary in 1939, from 1945 to the Soviet Union). After 1945, Czechoslovakia was under the political influence of the Soviet Union, was part of the so-called Eastern Bloc as a satellite state, and from 1955 was a member of the Warsaw Pact. Between 1960 and 1990, the communist country's official name was Czechoslovak Socialist Republic (abbreviated ČSSR). The democratic political change was initiated in 1989 with the Velvet Revolution and resulted in the establishment of the independent Czech and Slovak republics in 1992.
The Soviet Union (SU or USSR, Russian: Союз Советских Социалистических Республик (СССР) was a state in Eastern Europe, Central and Northern Asia existing from 1922 to 1991. The USSR was inhabited by about 290 million people and formed the largest territorial state in the world, with about 22.5 million square km. The Soviet Union was a socialist soviet republic with a one-party system.
Yugoslavia was a southeastern European state that existed, with interruptions and in slightly changing borders, from 1918 to 1992 and 2003, respectively. The capital and largest city of the country was Belgrade. Historically, a distinction is made in particular between the period of the Kingdom of Yugoslavia from 1918 to 1941 (also called 'First Yugoslavia') and communist Yugoslavia from 1945 (the so-called 'Second Yugoslavia') under the dictatorial ruling head of state Josip Broz Tito (1892-1980). The disintegration of Yugoslavia from 1991 and the independence aspirations of several parts of the country eventually led to the Yugoslav Wars (also called the Balkan Wars or post-Yugoslav Wars). Today, the successor states of Yugoslavia are Slovenia, Croatia, Serbia, Montenegro, North Macedonia, Kosovo and Bosnia and Herzegovina.