The Recovered Territories or Regained Lands (Ziemie Odzyskane), are the former eastern territories of Germany and the Free City of Danzig which were annexed by Poland after World War II, at which time most of their German inhabitants were forcibly deported.
The rationale for the term "Recovered" was that these territories formed part of the Polish state, and were lost by Poland in different periods over the centuries. It also referred to the Piast Concept that these territories were part of the traditional Polish homeland under the Piast dynasty (there were their small parts under Poland even after the Piast ended), after the establishment of the state in the Middle Ages. Over the centuries, however, they had become predominantly German-speaking through the processes of German eastward settlement (Ostsiedlung), political expansion (Drang nach Osten), as well as language shift due to Germanisation of the local Polish, Slavic and Baltic Prussian population. Therefore, aside from certain regions such as West Upper Silesia, Warmia and Masuria, as of 1945 most of these territories did not contain sizeable Polish-speaking communities.
While most regions had long periods of Polish rule, spanning hundreds of years, some were controlled by Polish dukes and kings for short periods of up to several decades at a time. Various regions, when not under Polish rule, were in different times under the authority of the Bohemian (Czech) Kingdom, Hungary, Austria, Sweden, Denmark, Brandenburg, Prussia, and the German Reich. Many areas were also part of various Polish-ruled duchies, created as a result of the fragmentation of Poland, which began in the 12th century.
The great majority of the previous inhabitants either fled from the territories during the later stages of the war or were expelled by the Soviet and Polish communist authorities after the war ended, although a small German minority remains in some places.