Islam
Saladin
Saladin (Salah ad-Din) was not an Arab, he was a Kurd. He became involved in Egyptian affairs while still quite young (his early twenties). His uncle, Shirkuh, saw an opportunity in 1163 in the unsettled political conditions there and undertook to interfere with the somewhat reluctant blessing of Nuradin.
Two rivals were competing to control the wazirate and therefore the caliphate in Egypt. Currently installed was one Dirgham, who had seized power from another fellow named Shawar. It was Shawar who had fled to Nuradin at Damascus to plead for help, and it was Shawar whom Shirkuh accompanied in April 1164. The invasion was successful. Dirgham was killed and Shawar was restored as wazir.
The next four years were politically complex. Essentially, Shawar felt threatened by both Nuradin and by King Amalric of the Franks, so he wound up allying first with one and then with the other. He played the game badly, though. All that transpired was one invasion after another, either by Amalric or by Shirkuh (on behalf of Nuradin), and sometimes by both. The cities of the lower Nile bled and all sides suffered defeat, but eventually Shirkuh emerged the victor. Amalric and the Franks lacked the manpower to hold Cairo, while Shawar lacked the political skill. In the final invasion, January 1169, Cairo fell to Shirkuh and Shawar was arrested and executed. Shirkuh was briefly wazir, but he was old and obese and died only a few weeks later. The position of wazir fell to Saladin, now about 30 years old.