I read Amin Maalouf's The Crusades through Arab Eyes, and I understand that Egypt went through great turmoil with invasions by the Catholic crusaders and Turkish, Kurdish, and Arab Sunni Muslims, until it was eventually conquered by Shirkuh and his nephew, Saladin, ushering in the Ayubbid rule in Egypt. Eventually, after further Crusader invasions and Mongol invasions, the Mamluk Sultanate came to rule Egypt.

I'm just rushing through the details, but my question is, how did this Shia area transition to the Sunni branch of the religion? Was there an effort by Saladin and his successors to convert the populace? What was the process for the change?