Upper Silesia
Since the 9th century, Upper Silesia has been part of (chronologically) Greater Moravia, the Duchy of Bohemia, the Piast Kingdom of Poland, again of the Lands of the Bohemian Crown and the Holy Roman Empire, as well as of the Habsburg Monarchy from 1526. In 1742 the greater part of Upper Silesia was annexed by the Kingdom of Prussia, and in 1871 it became part of the German Empire. After the First World War the region was divided between Poland (East Upper Silesia) and Germany (West Upper Silesia). After the Second World War, West Upper Silesia also became Polish as the result of the Potsdam Conference.