Trans-Olza
Trans-Olza (Polish: Zaolzie, [zaˈɔlʑɛ] ; Czech: Záolží, Záolší; German: Olsa-Gebiet), also known as Trans-Olza Silesia (Polish: Śląsk Zaolziański), is a territory in the Czech Republic which was disputed between Poland and Czechoslovakia during the Interwar Period. Its name comes from the Olza River.