The Elbe Sandstone Mountains, also called the Elbe sandstone highlands is a mountain range straddling the border between the state of Saxony in southeastern Germany and the North Bohemian region of the Czech Republic, with about three-quarters of the area lying on the German side. The mountains are also referred to as Saxon Switzerland and Bohemian Switzerland in both German and Czech (Sächsische Schweiz and Böhmische Schweiz in German, Saské Švýcarsko and České Švýcarsko in Czech) or simply combined as Saxon-Bohemian Switzerland. In both countries, the mountain range has been declared a national park. The name derives from the sandstone which was carved by erosion. The river Elbe breaks through the mountain range in a steep and narrow valley.