Cieszyn Silesia, Těšín Silesia or Teschen Silesia (Polish: Śląsk Cieszyński [ˈɕlɔ̃sk tɕɛˈʂɨj̃skʲi] (listen); Czech: Těšínské Slezsko [ˈcɛʃiːnskɛː ˈslɛsko] (listen) or Těšínsko [ˈcɛʃiːnsko] (listen); German: Teschener Schlesien or Olsagebiet) is a historical region in south-eastern Silesia, centered on the towns of Cieszyn and Český Těšín and bisected by the Olza River. Since 1920 it has been divided between Poland and Czechoslovakia, and later the Czech Republic. It covers an area of about 2,280 square kilometres (880 sq mi) and has about 810,000 inhabitants, of which 1,002 square kilometres (387 sq mi) (44%) is in Poland, while 1,280 square kilometres (494 sq mi) (56%) is in the Czech Republic.