Most forests in Iran are located in the northern regions of the country and in the south of the Caspian Sea. These forest areas have sultry temperate climate and are drawn from the east of Ardebil province to the northern Khorasan province, along with three Gilan, Mazandaran and Golestan provinces. The Alborz mountain range, the highest mountain range in the Middle East, stands as a wall against the humidity caused by the Caspian Sea and prevents them from penetrating into the central parts of Iran, so these clouds are forced to rain in the northern regions, and the central areas become dry and desert.
There are 3, 400, 000 or three million and four hundred thousand hectares of forest on the northern slopes of the Alborz Mountains and Caspian Sea Provinces. The area of other forests that are scattered around the country is up to three million hectares. Of these forests, only 1, 3 million hectares are usable for industrial exploitation, the rest of the forests are not exploited due to lack of proper maintenance or natural damage. According to available documents, from ancient times to the beginning of the eighteenth century, Iran had many forests. The area of the forests existing in Iran with the current Achaemenid borders reached more than 16 million hectares. Destruction of the Iranian forests since the Mongol invasion began, and in particular in the last three centuries it reached its highest level. During the Qajar period between 1281 and 1291, 130 thousand tons of charcoal were mined from the cutting of Iranian forest trees