The Muslims saw three Christian emirs, strutting with their horses, in front of their armies, while breaking in the gates of Damascus, and touring the streets of this Islamic great city. I mean Kitbuqa, the leader of the Tatarian army, along with Hetom, the king of Armenia, and Bohemond, the emir of Antioch. They all entered this Muslim glorious city. It was the first time Christian emirs entered this city since the Roman army commanders left it during the era of Heraclius, the Caesar of Byzantines, and the Muslims conquered it in 14 A.H.; and there is no strength and no power save in Allaah!
The Tatars granted real security to the inhabitants of Damascus, and killed none of them, save those who held fast by the castle, after several weeks of siege. The Tatars then overthrew the castle and killed all who were in it.

Damascus fell at the end of Safar in 658 A.H., two years after the fall of Baghdad. It was indeed a record time, during which the Tatars invaded vast territories, and overthrew many cities in Turkey, Iraq and Syria. It is true that the main cities were Baghdad, Aleppo and Damascus, but the other cities were not easy. Furthermore, the population density of those regions was very high, due to their fertility, long history, high living conditions, and great civilization.
Consequently, the spirits of the Muslims became very low, and most of them became certain that it would be impossible to defeat the Tatars, and that there remained only a very few moments to the end of the lifetime of the Islamic Ummah.

The Tatars then started to administer Damascus with the help of the Christians, after having ruined its walls and castles.
Iblisian, a Tatarian, was appointed the governor of Damascus, who, though not a Christian, highly respected and was biased to the Christians. The city then started an amazing period in its history.

https://en.islamstory.com/index.php/en/artical/20822/damascus-after-its-fall