Český Těšín or Czech Teschen (Czech pronunciation: [ˈtʃɛskiː ˈcɛʃiːn]; Silesian: Czeski Ćeszyń, Polish: Czeski Cieszyn , German: Tschechisch-Teschen) is a town in the Karviná District, Moravian-Silesian Region of the Czech Republic. The town is commonly known in the region as just Těšín (Silesian: Ćeszyń, Polish: Cieszyn). It lies on the west bank of the Olza river, in the heart of the historical region of Cieszyn Silesia. Until the 1920 division of the region between Poland and Czechoslovakia it was just a western suburb of the town of Teschen, which after the division fell to Poland as Cieszyn.