The German Democratic Republic (GDR; German: Deutsche Demokratische Republik or DDR), informally known as East Germany (German: Ostdeutschland), was a socialist state established by the USSR in 1949 in the Soviet zone of occupied Germany, including East Berlin of the Allied-occupied capital city. The GDR had an area of 107,771 km² (41,610 mi²), bordering Czechoslovakia to the south, West Germany to the south and west, Poland to the east, and the Baltic Sea to the north. East Germany was dissolved upon joining the institutions of West Germany in the German reunification, on 3 October 1990.