Karadagh
There is no evidence on Google Maps of a village close to Alexandropol (now called Gyumri) with the name Karadagh. The name is Turkish and means Black Mountain. It is possible that the village was renamed or merged into Gyumri.
The area known as Arasbaran which stretches from the Qusha Dagh massif, south of Ahar, to the Aras River in East Azerbaijan Province of Iran is also known as Karadagh. It seems unlikely that Gurdjieff is referring to that in the text, but it is worth noting.