History of Poland
The Polish People's Republic ("Polska Rzeczpospolita Ludowa") was established under the rule of the communist Polish United Workers' Party (PZPR). The name change from the Polish Republic was not officially adopted, however, until the proclamation of the Constitution of the Polish People's Republic in 1952.
Territorial evolution of Poland
The Poles are the most numerous of the West Slavs and occupy what some believe to be the original homeland of the Slavic peoples. While other groups migrated, the Polanie remained "in situ" along the Vistula, from the river's sources to its estuary at the Baltic Sea. There is no other European nation centred to such an extent on one river. The establishment of a Polish state is often identified with the adoption of Christianity by Mieszko I in 966 CE (see Baptism of Poland), when the state covered territory similar to that of present-day Poland. In 1025 CE, Poland became a kingdom. In 1569, Poland cemented a long association with the Grand Duchy of Lithuania by signing the Union of Lublin, forming the Polish–Lithuanian Commonwealth. The Polish–Lithuanian Commonwealth was one of the largest and most populous countries in 16th- and 17th-century Europe.