Ain Tamer, Quraqir, Suwa, Arak, and the historical city of Tadmur were first to fall to Khalid. Sukhnah, al-Qaryatayn and Hawarin were captured after the Battle of al-Qaryatayn and the Battle of Hawarin. After dealing with all these cities, Khalid moved towards Damascus through a mountain pass which is now known as Sanita-al-Uqab (Uqab Pass) after the name of Khalid's army standard. From here he moved away from Damascus, towards Bosra, the capital of the Ghassanids. He ordered other Muslim commanders to concentrate their armies, still near the Syrian-Arabian border, at Bosra. At Maraj-al-Rahab, Khalid defeated a Ghassanid army in a quick battle, called the Battle of Marj-al-Rahit. Meanwhile, Abu Ubaida ibn al-Jarrah, the supreme commander of the Muslim armies in Syria, had ordered Shurhabil ibn Hasana to attack Bosra. The latter laid siege to Bosra with his small army of 4000. The Roman and Ghassanid Arab garrison, realizing that this might be the advance guard of the larger Muslim army to come, sallied out of the fortified city and attacked Shurhabil, surrounding him from all sides; however, Khalid reached the arena with his cavalry and saved Shurhabil. The combined forces of Khalid, Shurhabil, and Abu Ubaidah then resumed the siege of Bosra, which surrendered some time in mid-July, effectively ending the Ghassanid Dynasty.