sentences:  An-Nasir Yusuf, being an Ayyubid, refused to recognize Shajar al-Durr as the Sultana of Egypt and, as a sign of support, the Emirs of Syria granted him the city of Damascus, in Syria.Alarmed by these developments, the Mamluk leaders in Egypt decided to replace Shajar al Durr with the Atabek (commander in chief) Aybak.In October 1250 an-Nasir Yusuf sent forces to Gaza to conquer Egypt and overthrow Aybak, but Egyptian forces led by Faris ad-Din Aktai defeated them.