Simplify the following text for a Grade 7 native English-speaking person.
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 .