The Alborz mountain range from the west begins from the city of Talesh, Azerbaijan, and follows the east to Turkmenistan and Afghanistan.
A large part of the Alborz is drawn along the southern side of the Caspian Sea. In this section, the northern part of the Alborz is green and its southern side is dry. The main reason for this dichotomy is the existence of the Alborz mountain range, which, like a natural barrier, prevents moisture passing from the Caspian Sea to the south, and most of this moisture falls on the northern side of the Alborz.
The highest mountain of Alborz is Mount Damavand (5671 m), which is located in the city of Rinne, Mazandaran province. The slopes and valleys of Alborz are the most important promenades in the provinces of Tehran, Karaj, Qazvin and Semnan. The main river of the northern slopes of the Alborz is Sefidrud and the southern slopes are Karaj and Jajrood rivers.