Former eastern territories of the German Reich

History of Brandenburg and Prussia
Northern March pre–12th century		Old Prussians pre–13th century
Margraviate of Brandenburg 1157–1618 (1806)		Teutonic Order 1224–1525
		Duchy of Prussia 1525–1618	Royal (Polish) Prussia 1466–1772
Brandenburg-Prussia 1618–1701
Kingdom in Prussia 1701–1772
Kingdom of Prussia 1772–1918
Free State of Prussia 1918–1947			Klaipėda Region (Lithuania) 1920–1939 / 1945–present
Brandenburg (Germany) 1947–1952 / 1990–present	Recovered Territories (Poland) 1918/1945–present	Kaliningrad Oblast (Russia) 1945–present

The former eastern territories of Germany (German: Ehemalige deutsche Ostgebiete) are those provinces or regions east of the current eastern border of Germany (the Oder–Neisse line) which were lost by Germany after World War I and then World War II.

The territories lost following World War I include most of the Province of Posen and West Prussia. Further territories lost after World War II include East Prussia, Farther Pomerania, Neumark, Upper Silesia, and almost all of Lower Silesia. All territories lost in both World Wars account for 33% of the former German Empire, while land ceded by Germany after World War II constituted roughly 25% of its pre-war Weimar territory. In present-day Germany, the term usually refers only to the territories lost in World War II. Territories acquired from Germany after World War II were called the "Recovered Territories". These territories had been ruled as part of Poland by the Piast dynasty in the High Middle Ages, with the exception of East Prussia which was inhabited by Old Prussians.

The post-war border between Germany and Poland along the Oder–Neisse line was formally recognized by East Germany in 1950 by the Treaty of Zgorzelec, under pressure from Stalin. In 1952, recognition of the Oder–Neisse line as a permanent boundary was one of Stalin's conditions for the Soviet Union to agree to a reunification of Germany (see Stalin Note). The offer was rejected by West German Chancellor Konrad Adenauer. The official West German government position on the status of former eastern territories of Germany east of the Oder and Neisse rivers was that the areas were "temporarily under Polish [or Soviet] administration." In 1970, West Germany recognised the line as a de facto boundary in the Treaty of Warsaw.

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