The Arabic term Iraq was not used at this time; in the mid-6th century the Iranian Empire under Sasanian dynasty was divided by Khosrow I into four quarters, of which the western one, called Khvārvarān, included most of modern Iraq, and subdivided to provinces of Meshan, Asuristan, Adiabene and Media.
The area of modern Iraq north of Tikrit was known in Muslim times as Al-Jazirah, which means "The Island" and refers to the "island" between the Tigris and Euphrates rivers.