Adiabene was a kingdom in the upper Tigris region of Assyria with its capital at Arbela (modern-day Arbil in the Kurdistan region of Iraq). Located near the Parthian (Persian) empire’s northern border, Adiabene functioned as a vassal kingdom to the Parthian empire during the Hellenistic period. In the first century B.C.E., it became independent but continued to function nominally as a dependent of the Parthian empire.