أمير المؤمنين
After friendly correspondence with the caliph at Baghdad, whom he acknowledged as "Amir al-Mu'minin" ("Commander of the Faithful"), Yusuf ibn Tashfin in 1097 assumed the title of "Amir al Muslimin" ("Commander of the Muslims"). He died in 1106, when he was reputed to have reached the age of 100. The Almoravid power was at its height at Yusuf's death: the Moorish empire then included all of Northwest Africa as far eastward as Algiers, and all of Iberia south of the Tagus and as far eastward as the mouth of the Ebro, and including the Balearic Islands.