The Kopet-Dag Mountains, also known as the Turkmen-Khorasan Mountains, mark the border between Turkmenistan and Iran. It stretches from near the Caspian Sea northwest-southeast. The highest point is known as Kūh-e Qūchān (3'190 m) in Iran.
Iran 2013, Khatoon Bridge in Khorasan.
It is not confirmed, but it seems the location is probably at (35° 57' 52.13" N 61° 07' 09.49" E) the north of the Doosti dam at the border to Turkmenistan. A view towards south.