Original: The Mamluks, led by their new sultan Baibars, quickly became a regional power in the Middle East by capturing a number of crusader states and repulsing Mongol attacks.
Simplified: The Mamluks were led by their new sultan Baibars. The Mamluks were soon were more in control in the Middle East because they took control of a number of crusader states and also stopped the Mongol attacks from happening as much.