This area used by to be inhabited by Germans, who had been invited by Czech kings in the early Middle Ages. This area had a German majority and was called ''Sudety'' (Sudetenland). It was one of the wealthiest and most industrialized regions in Austria-Hungary and then Czechoslovakia. Before the beginning of World War II, in 1938, Sudetenland was annexed by Nazi Germany. After the war, the whole German population of 3 million people was deported to Germany, and the region was resettled by Czechs from outside the region. Today, as a result of the expulsion of Germans and four decades of communism (during which part of the landscape was destroyed by coal mining), this region is one of the poorest parts of the Czech Republic, and it has a relatively high unemployment rate. Large German villas, these days often abandoned, are reminders of its wealthier past. The North Bohemian landscape is stunning. On the borders with Germany and Poland are the Ore Mountains (Krusne hory), Lusatian Mountains (Luzicke hory) and Jizera Mountains (Jizerske hory). The Elbe valley, also located here, is the lowest point in the Czech Republic. The Central Bohemian Mountains (Ceske Stredohori) are of volcanic origin, and can be found with rock structures in the Bohemian Switzerland National Park.