Upper Silesia language used Silesian
Bohemia, Austria and Prussia
In 1327 the Upper Silesian dukes, like most of their Lower Silesian cousins, had sworn allegiance to King John of Bohemia, thereby becoming vassals of the Bohemian kingdom. During the re-establishment of Poland under King Casimir III the Great, all Silesia was specifically excluded as non-Polish land by the 1335 Treaty of Trentschin becoming a land of the Bohemian Crown and — indirectly — of the Holy Roman Empire. By the mid-14th century, the influx of German settlers into Upper Silesia was stopped by the Black Death pandemic. Unlike in Lower Silesia, the Germanization process was halted; still a majority of the population spoke Polish and Silesian as their native language, often together with German (Silesian German) as a second language. In the southernmost areas, also Lach dialects were spoken. While Latin, Czech and German language were used as official languages in towns and cities, only in the 1550s (during the Protestant Reformation) did records with Polish names start to appear.
Upper Silesia was hit by the Hussite Wars and in 1469 was conquered by King Matthias Corvinus of Hungary, while the Duchies of Oświęcim and Zator fell back to the Polish Crown as a part of Lesser Poland. Upon the death of the Jagiellonian king Louis II in 1526, the Bohemian crown lands were inherited by the Austrian House of Habsburg. In the 16th century, large parts of Silesia had turned Protestant, promoted by reformers like Caspar Schwenckfeld. After the 1620 Battle of White Mountain, the Catholic Emperors of the Habsburg dynasty forcibly re-introduced Catholicism, led by the Jesuits.
language spoken official language linguistic usage dialect spoken vernacular employed