Avdallar is a a village in the Iravan uezd of the former Iravan governorate, later in the former Ellar (Kotayk, Abovyan) district, and currently in the Kotayk province. The provincial centre lies 58 km to the southwest of the town of Ellar, 11-12 km to the north of the city of Iravan, and at a height of 1,400 m above sea level. Another name for the village is “Abdalar”.

The village was solely inhabited by Azerbaijanis: 59 in 1873, 112 in 1886, 115 in 1897, 131 in 1904, 194 in 1914 and 192 Azerbaijanis in 1916. In 1918 the Azerbaijanis were deported having been exposed to Armenian aggression, and the Armenians removed from the province of Van of Türkiye in 1918–1919 were settled in the place. The surviving inhabitants of the village managed to return to their land only following the establishment of Soviet power in the present-day Armenian territory. Along with the Armenians, the village was inhabited by 29 Azerbaijanis in 1922, seven in 1926, six in 1931. According to the decision of the USSR Council of Ministers “On the resettlement of collective farmers and other Azerbaijani population from the Armenian SSR in the Kur-Araz lowland of the Azerbaijan SSR” dated 23 December 1947, the Azerbaijanis were removed from the village in 1948–1949. At present, Armenians live in the village.

The toponym was coined by adding the suffix “-ar” denoting plurality to the name of the Turkic Abdal tribe. It implies “a village belonging to the Abdals, the Abdal tribe”. It is an ethnotoponym.

By the decree of the Presidium of the Supreme Soviet of the Armenian SSR dated 4 April 1946, the village was renamed “Hatsavan”. According to the law “On the administrative-territorial division of the Republic of Armenia” dated 7 November 1995, it was integrated into the administrative area of the Kotayk province.

Geographic coordinates: latitude: 40°08′ N., longitude: 44°39′ E.