In medieval history, Iraq ( ) was the area comprising the lower parts of Mesopotamia, being roughly equivalent in size and shape to the ancient region of Babylonia. It was bounded to the northwest by al-Jazira, to the north by Adharbayjan (the Sassanid Aturpatakan), to the northeast by al-Jibal, to the east by al-Ahwaz, to the southeast by the Sea of Fars (the Persian Gulf), and to the southwest by the desert of Arabia.