Arzanene (Greek: Ἀρζανηνή), in Armenian Aghdznik or Altzniq (Armenian: Աղձնիք Ałjnikʿ), was a historical region in southwestern Greater Armenia. It covered an area of 17,530 km2 (7,000 sq mi).
Under the independent Armenian Kingdom (2nd century BC – 4th century AD), Arzanene was divided into 11 cantons with their main town-castles:
Arzanene had a warm climate, and was famous for its rivers and springs, as well as its iron and lead mines. Cattle-breeding, grape cultivation and wine making were well-developed. In 298 AD, part of Arzanene was conquered by the Roman Empire, while the 387 Peace of Acilisene gave the rest of the region, except for the Aghdzn district, to the Romans as well. By 591, all of Arzanene had been annexed by the East Roman or Byzantine Empire. In the place of destroyed Tigranakert, the Romans built a new city named Martyropolis or Nprkert. During the Arab conquest of Armenia, many Arab tribes settled in Arzanene. The Armenian population remained in the mountainous parts until the Armenian Genocide in 1915.