Atgiz was a village in the territory of the Zangezur uezd of the former Yelizavetpol (Ganja) governorate, later in the former Gafan district, and present-day Syunik province. It was located on the left bank of the Okhchu River, 2 km to the north of the village of Okhchu, on the mountain slope, to the southwest of Pirhamza Mountain, and 2 km to the north of Gafan-Gejalan highway. The village was merged with the town of Gajaran in 1959. It was marked on the five-verst map of the Caucasus.

The village was inhabited by 37 Azerbaijanis in 1831, 105 in 1873, 120 in 1886, 242 in 1897, 198 in 1908, and 36 Azerbaijanis in 1914. The Azerbaijanis were deported from the village in 1916–1918. After the establishment of Soviet power in present-day Armenia, the Azerbaijanis were able to return to the village. The village was inhabited by 74 Azerbaijanis in 1926 and 101 Azerbaijanis in 1931. It was abolished in 1980.

The toponym was coined on the basis of the ethnonym “Giz” which is a phonetic variation of the name of the Oghuz Turkic tribe.