East Upper Silesia (German: Ostoberschlesien) is the easternmost extremity of Silesia, the eastern part of the Upper Silesian region around the city of Katowice (German: Kattowitz).[1] The term is used primarily to denote those areas that became part of the Second Polish Republic on 20 June 1922, as a consequence of the post-World War I Treaty of Versailles. Prior to World War II, the Second Polish Republic administered the area as Autonomous Silesian Voivodeship. East Upper Silesia was also known as Polish (Upper) Silesia, and the German (Upper) Silesia was known as West Upper Silesia.