Gachaghan is a village in the Borchali uezd of the former Tiflis governorate, later in the former Allahverdi (Tumanyan) district, and currently in the Lori province. The provincial centre lies 16 km to the southwest of the town of Boyuk Garakilsa (Vanadzor), adjacent to the Dashbulag River, at the foot of Devedashi Mountain, at a height of 1270 m above sea level. It was marked on the five-verst map of the Caucasus.

Following the settlement of Armenians in the village, the Azerbaijani population of the village gradually left their lands. The toponym was coined from the name of the Gachaghan Turkic tribe.

By the decree of the Presidium of the Supreme Soviet of the Armenian SSR dated 25 January 1978, was renamed “Arevatsag”. According to the law “On the administrative-territorial division of the Republic of Armenia” dated 7 November 1995, it was integrated into the administrative territory of the Lori province.

Geographical coordinates: latitude: 40°58’ N., longitude: 44°36’ E.