The Shia Ismailis form the largest branch of Shia Islam in Syria, forming 3% of Syria's population. The split from the greater branch occurred over the recognition of the Seventh Imam. Shia Ismailis believe that Ja'far al-Sadiq, the Sixth Imam, appointed Isma'il to be the Seventh Imam, a line that continues unbroken to the present day, the office currently sitting with His Highness the Aga Khan. The Shia Ithna Asharia, however, believe that Jafar appointed Isma'il's brother Musa al Kadhim to be the Seventh Imam, a line of Imamat that ended with the 12th Imam of the Ithna Asharia. Little is known of the early history of the sect, but it was firmly established by the end of the ninth century. From 969 to 1171, an Ismaili dynasty, the Fatimids, ruled as caliphs in Egypt. The Ismaili power in Syria was stamped out by the Mamluk dynasty of Egypt, after the former offered the Crusaders their allegiance and conversion to Christianity – which were rejected by the Knights Templar.