”Darvaz” means “Gate” in Persian language, and the district of Darvaz in Badakhshan (on both sides of the river Panj) was indeed the gate from the Western Pamirs to ancient Bactria and Khorazm (and to the later Emirate of Bukhara).
The territory of Darvaz lying on the Panj is the lowest in Gorno-Badakhshan. The fortress that gave it name to Kalai-Khumb (“Kala”-fortress, “”Khumb-jar), located on the left bank of the Khumbob river just above the confluence with the Panj.
For a long time Darvaz was the most important of the kingdoms along the Amu Darya (Oxus) whose rulers claimed that their descendants were Macedonians.
87km south of Kalai-Khumb the river Vanj joins the Panj. The gorge of the Panj is narrower and steeper between Kalai-Khumb and the Vanj valley and passes within view of a number of Afghan villages and of the precipitous paths clinging to the cliff face on the Afghan side, known locally as Ovrings.