The Bohemian Massif; or Ceský masiv; is in the geology of Central Europe a large massif stretching over central Czech Republic, eastern Germany, southern Poland and northern Austria. It is surrounded by four ranges: the Ore Mountains (Krušné hory, or Erzgebirge) in the northwest, the Sudetes (for example Krkonoše, Hrubý Jeseník) in the northeast, the Bohemian-Moravian Highlands (Ceskomoravská vrchovina) in the southeast, and the Bohemian Forest (Šumava) in the southwest. The massif encompasses a number of mittelgebirges and consists of crystalline rocks, which are older than the Permian (more than 300 million years old) and therefore deformed during the Variscan Orogeny.