Opavian Silesia

Opavian Silesia (Czech: "Opavské Slezsko", Polish: "Śląsk Opawski" or "Śląsk karniowsko-opawski", German: "Troppauer Schlesien" or "Troppauer Land") is a historical subregion of Silesia (Upper Silesia) currently split between Poland and the Czech Republic. 
The historical centre of the region is Opava (Polish: "Opawa", German: "Troppau") and the region mostly encompasses areas of the medieval Duchy of Opava. 
The Hlučín Region is located within Opavian Silesia.
Formerly, Lach used to be spoken in Opavian Silesia.
History.
20th and 21st centuries.
After the First World War, most of Austrian Silesia (including Opavian Silesia) became a part of the newly formed Czechoslovakia. Hlučínsko, a part of Germany, became a part of Czechoslovakia on On February 4, 1920 without a referendum. This was largely due to the fact that most of the regions inhabitants spoke Czech. Leobschütz (Polish: "Głubczyce", Czech: "Hlubčice" or "Glubčice"), a town in northern Opavian Silesia, was supposed to come under the administration of Czechoslovakia if the rest of the Upper Silesian Plebiscite area fell to Poland. That however never happened, and after the Second World War Leobschütz/Głubczyce found itself within Poland.
From 1945 to 1946, the majority of the German population of Opavian Silesia was expelled.