 The campaign was ended in early January 638.After the defeat of pro-Byzantine Christian Arabs from Al Jazira, who laid the siege of Emessa in March 638, Abu Ubaidah sent more columns under Khalid ibn Walid and Iyad ibn Ghanm to subdue Jazira near the Syrian frontiers and in Anatolia.These columns went northwards as far as the Ararat plain and west towards the Taurus Mountains.