The Battle of the Zab (Arabic: معركة الزاب), also referred to in scholarly contexts as Battle of the Great Zāb River, took place on January 25, 750, on the banks of the Great Zab River in what is now the modern country of Iraq. It spelled the end of the Umayyad Caliphate and the rise of the Abbasids, a dynasty that would last from 750 to 1258 which is divided in to two periods: Early Abbasid period (750–940) and Later Abbasid period (940–1258).