 Over 20% of all inhabitants were Poles expelled from areas of Eastern Poland annexed by the USSR.The rest were mostly people from neighbouring areas located right next to East Prussia (almost 44% came from Masovia, Sudovia, Podlachia and pre-war Polish Pomerania) and southern Poland (~16%).In April 1946, northern East Prussia became an official province of the Russian SFSR as the ""Kyonigsbergskaya Oblast"", with the Memel Territory becoming part of the Lithuanian SSR.