Dena mountain range with a length of seventy kilometers is a part of Zagros mountain range which is stretched between Semirom from Isfahan province and Yasuj from Kohgiluyeh province and Boyer Ahmad from northwest to southeast. Dena mountain range has more than 40 peaks with an altitude of more than 4000 meters. The highest peak of this mountain range is called Qash Mastan, which is 4450 meters above sea level.
The beginning of the trek to climb Qash Mastan peak is from Khafr village at an altitude of 2200 meters on the northern slope of this peak. A relatively small shelter is located in the middle of the ascent to the peak of Qash Mastan.
A stream also flows upstream of the shelter, which consists of melting glacial snow.
A large part of the way to climb the peak of Qash Mastan must be climbed up from a long glacier. This glacier completely covers the valley floor of the route. Dena mountain range has many glaciers.
To reach Khafr village, the origin of climbing Qash Mastan peak, you have to move from Semirom to Yasuj. About forty kilometers from the Semirom to Yasuj road, you will encounter a crossroad. You must choose the road on the left that leads to Hana. After 15 km, you will come to another crossroad. this time you have to enter the road on the right, which finally after another 15 km and after crossing the bridge from Marbar river, you will reach Khafr village.