Mountain range in northern Iran, reacing peaks of 5,604 metres. The range is about 900 km long, its width varies from 30 up to 130 km, formed as an arc south of the Caspian Sea. It begins at the borders to Armenia in the west, ending at the borders to Turkmenistan in the east.
The mountain range divides the region into two climatic zones. The northern, along the Caspian Sea benefits from moisture from the sea as well as rainfall, The southern region, has a more arid climate, with precipitation between 280 and 500 mm. Vegetation is poor, but historically juniper forests were common.