The conquest of Jazirah was completed by 640 CE, after which Abu Ubaidah sent Khalid and Iyad ibn Ghanm (conqueror of Jazirah) to invade Byzantine territory north of there. They marched independently and captured Edessa, Amida, Malatya and the whole of Armenia up to Ararat and raided northern and central Anatolia. Heraclius had already abandoned all the forts between Antioch and Tartus to create a buffer zone between the Muslim controlled areas and Anatolia. Umar then called a halt to the expedition and ordered Abu Ubaidah, now governor of Syria, to consolidate his rule there. This decision can be explained by the dismissal of Khalid from the army, which ended his military career, and a drought followed by a plague the year after.