(in Armenian, Tsopk; from Urartian Tsopani), a historical region of Armenia, situated between the western Euphrates (Kara Su) River and the western Tigris River. An Armenian kingdom arose in Sophene in the third century B.C. Originally a province of the Seleucids, it became independent in 190 B.C. In 94 B.C., Tigranes II incorporated the region into Greater Armenia. Under the Armenian Arsacids, Sophene was part of the royal domain; the kings’ treasures were kept in Sophene, in Bnabel Castle. In 387, Sophene passed by Byzantium in accordance with a treaty that partitioned Armenia.