Silesia (/sɪˈliːʒə, -ʃə, saɪ-/; Czech: Slezsko; Silesian: Ślůnsk [ɕlonsk]; Latin: Silesia) is a region of Central Europe located mostly in Poland, with small parts in the Czech Republic and Germany. Its area is about 40,000 km2 (15,444 sq mi), and its population about 8,000,000. Silesia is located along the Oder River. It consists of Lower Silesia and Upper Silesia.
The region is rich in mineral and natural resources, and includes several important industrial areas. Silesia's largest city and historical capital is Wrocław. The biggest metropolitan area is the Upper Silesian metropolitan area, the centre of which is Katowice. Parts of the Czech city of Ostrava fall within the borders of Silesia.
Silesia's borders and national affiliation have changed over time, both when it was a hereditary possession of noble houses and after the rise of modern nation-states. The first known states to hold power there were probably those of Greater Moravia at the end of the 9th century and Bohemia early in the 10th century. In the 10th century, Silesia was incorporated into the early Polish state, and after its division in the 12th century became a Piast duchy. In the 14th century, it became a constituent part of the Bohemian Crown Lands under the Holy Roman Empire, which passed to the Austrian Habsburg Monarchy in 1526.
Most of Silesia was conquered by Prussia in 1742, later becoming part of the German Empire and subsequent German republic up to 1945. The varied history with changing aristocratic possessions resulted in an abundance of castles in Silesia, especially in the Jelenia Góra valley. After World War I, the easternmost part of this region, i.e. an eastern strip of Upper Silesia, was awarded to Poland by the Entente Powers after insurrections by Poles and the Upper Silesian plebiscite. The remaining former Austrian parts of Silesia were partitioned to Czechoslovakia, and are today part of the Czech Republic. In 1945, after World War II, the bulk of Silesia was transferred, on demands of the Polish delegation, to Polish jurisdiction by the Potsdam Agreement of the victorious Allied Powers and became part of Poland. The small Lusatian strip west of the Oder-Neisse line, which had belonged to Silesia since 1815, remained in Germany. The largest town and cultural centre of this region is Görlitz.
Most inhabitants of Silesia today speak the national languages of their respective countries (Polish and Czech, both of which are Western Slavic languages, with some, albeit limited, mutual intelligibility). The population of Upper Silesia is native (with some immigrants from Poland who came in the 19th to 20th centuries), while Lower Silesia was settled by a German-speaking population before 1945. An ongoing debate exists whether Silesian speech should be considered a dialect of Polish or a separate language. Also, a Lower Silesian German dialect is used, although today it is almost extinct. It is used by expellees within Germany, as well as Germans who were left behind.
Czech Silesia (Czech: České Slezsko; Silesian: Czeski Ślůnsk; German: Tschechisch-Schlesien) is the name given to the part of the historical region of Silesia presently located in the Czech Republic. While not today an administrative entity in itself, Czech Silesia is, together with Bohemia and Moravia, one of the three historical Czech lands. In this context, it is often mentioned as "Silesia" even though it is only around one tenth of the area of the historic land of Silesia.
It lies in the north-east of the Czech Republic, predominantly in the Moravian-Silesian Region, with a section in the northern Olomouc Region. It is almost identical in extent with the Duchy of Upper and Lower Silesia, also known as Austrian Silesia before 1918; between 1938-1945, part of the area was also alluded to as Sudeten Silesia: a reference to the Sudetenland.
Czech Silesia borders Moravia in the south, Poland (Polish Silesia) in the north (in the northwest the County of Kladsko, until 1742-48 an integral part of Bohemia) and Slovakia in the southeast. With the city of Ostrava roughly in its geographic center, the area comprises much of the modern region of Moravian-Silesia (save for its southern edges) and, in its far west, a small part of the Olomouc Region around the city of Jeseník. After Ostrava, the most important cities are Opava and Český Těšín. Historically Český Těšín is the western part of the city of Cieszyn which nowadays lies in Poland.
Situated in the Sudetes, it is cornered by the Carpathians in the east. Its major rivers are the Oder (Czech: Odra), Opava and Olše (which forms part of the natural border with Poland).
The first Germanic settlements were built in the second century. Later the Germanic tribes moved west and Slavs came into the country. Modern-day Czech Silesia derives primarily from a small part of Silesia that remained within the Bohemian Crown and the Habsburg Monarchy at the end of the First Silesian War in 1742, when the rest of Silesia was ceded to Prussia. It was re-organised as the Duchy of Upper and Lower Silesia, with its capital at Opava (German: Troppau, Polish: Opawa). In 1900, the Duchy occupied an area of 5,140 km² and had a population of 670,000.
In 1918, the former Duchy formed part of the newly created state of Czechoslovakia, except the Cieszyn Silesia, which was split between Czechoslovakia and Poland in 1920, Czechoslovakia gaining its western portion. Hlučín Region (Czech: Hlučínsko, German: Hultschiner Ländchen), formerly part of Prussian Silesia, also became part of Czechoslovakia under the Treaty of Versailles in 1920.
Following the Munich Agreement of 1938, most of Czech Silesia became part of the Reichsgau Sudetenland and Poland occupied the Zaolzie area on the west bank of the Olza (the Polish gains being lost when Germany occupied Poland the following year).
With the exception of the areas around Cieszyn, Ostrava and Hlučín, Czech Silesia was predominantly settled by German-speaking populations up until 1945. Following the Second World War, Czech Silesia and Hlučínsko were returned to Czechoslovakia and the ethnic Germans were expelled. The border with Poland was once again set along the Olza (although not confirmed by treaty until 1958).
The population mainly speaks Czech with altered vowels. Some of the native Slavic population speak Lach, which is classed by Ethnologue as a dialect of Czech, although it also shows some similarities to Polish. In Cieszyn Silesia a unique dialect is also spoken, mostly by members of the Polish minority there.