Doupov Mountains is a cenozoic

Cenozoic

The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...

 volcanic mountain range

Mountain range

A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...

 with the typical structure of stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

. The centre of the stratovolcano was in the place of a former town of Doupov.

The highest mountain is Hradiště (934 metres), the lowest point is by the river Ohře

Ohre

The Ohře is a 316 km long river in Germany and the Czech Republic , left tributary of the Elbe. The basin area of the river has a size of 6,255 km², of which 5,614 km² are in the Czech Republic and 641 km² in Germany...

 near Kadaň

Kadan

Kadaň , is a city in the Ústí nad Labem Region of the Czech Republic.The city lies on the banks of the river Ohře. Although it is situated in an industrial part of the Czech Republic there is no major industry within the city and people usually work in offices or have to commute. There are two...

 (cca 275 metres).

In 1945 most of the German population was forced out

Expulsion of Germans after World War II

The later stages of World War II, and the period after the end of that war, saw the forced migration of millions of German nationals and ethnic Germans from various European states and territories, mostly into the areas which would become post-war Germany and post-war Austria...

 so that Doupov Mountains were almost completely unpopulated. It became the Army Training Area in 1953 and still serves this purpose for NATO forces.