Cieszyn Silesia or Těšín Silesia or Teschen Silesia (Polish: Śląsk Cieszyński , Czech: Těšínské Slezsko or Těšínsko , 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.
The historical boundaries of the region are roughly the same as those of the former independent Duchy of Teschen/Cieszyn. Currently, over half of Cieszyn Silesia forms one of the euroregions, the Cieszyn Silesia Euroregion, with the rest of it belonging to Euroregion Beskydy.
From an administrative point of view, the Polish part of Cieszyn Silesia lies within the Silesian Voivodeship and comprises Cieszyn County, the western part of Bielsko County, and the western part of the town of Bielsko-Biała.
Cieszyn [ˈt͡ɕɛʂɨn] (Czech: Těšín, German: Teschen, Yiddish: טעשין) is a border-town in southern Poland on the east bank of the Olza River, and the administrative seat of Cieszyn County, Silesian Voivodeship. The town has about 36,100 inhabitants (as of 2013), and lies opposite Český Těšín in the Czech Republic's Karviná District, Moravian-Silesian Region. Both towns belonged to the historical region of Austrian Silesia and are the historical capital of the region of Cieszyn/Těšín Silesia.
The town is situated on the Olza river, a tributary of the Oder River, which forms the border with the Czech Republic. It is located within the western Silesian Foothills north of the Silesian Beskids and Mt. Czantoria Wielka, a popular ski resort. Cieszyn is the heart of the historical region of Cieszyn Silesia, the southeasternmost part of Upper Silesia. Until the end of World War I in 1918 it was a seat of the Dukes of Teschen.
In 1920 Cieszyn Silesia was divided between the two newly created states of Poland and Czechoslovakia, with the smaller western suburbs of Teschen becoming part of Czechoslovakia as a new town called Český Těšín. The larger part of the town joined Poland as Cieszyn. Three bridges connect the twin towns. After Poland and the Czech Republic joined the European Union and its passport-free Schengen zone, border controls were abolished and residents of both the Polish and Czech part could move freely across the border. Both Polish and Czech part of the city have 61,201 inhabitants. Cieszyn is the southern terminus of the Polish National road 1 leading to Gdańsk on the Baltic coast.
Cieszyn may refer to the following places: