The conquest of Levant was completed in 637 after the last relentless resistance by Byzantines at Battle of Iron bridge, which resulted in Muslim occupation of Antioch, capital of eastern zone of Byzantine Empire in October 637. Emperor Heraclius attempt to capture northern Syria in 638, with the aid of Christian Arabs of Jazira, prompted Muslims to invade Jazira ("Mesopotamia") in 638 and captured it securing the eastern flank of Syria from Byzantine attacks in future, soon after the occupation of Jazira, Muslim columns marched north in Anatolia, invaded and plundered Byzantine provinces of Armenia, these were however only preemptive attacks on Armenia to eliminate all Byzantine presence north of Syria, Armenia was annexed in 643 During the Conquest of Persian Empire.