But there was another still more important development in progress. A missionary had gone to North Africa and there worked with success among the Berber tribes about Constantine, in what is now Algeria. These have always been ready for any change. He gave himself out as forerunner of the Mahdi, promised them the good of both worlds, and called them to arms. The actual rising was in A.H. 289 (A.D. 902). Then there appeared among them Sa‘id, the son of Ahmad, the son of Abd Allah, the son of Maymun the oculist; but it was not under that name. He was now Ubayd Allah al-Mahdi himself, a descendant of Ali and of Muhammad ibn Isma‘il, for whom his ancestors were supposed to have worked and built up this conspiracy. In A.H. 296 (A.D. 909) he was saluted as Commander of the Faithful, with the title of al-Mahdi. So far the conspiracy had succeeded. This Fatimid dynasty, so they called themselves from Fatima, their alleged ancestress, the daughter of Muhammad, conquered Egypt and Syria half a century later and held them till A.H. 567 (A.D. 1171). When in A.H. 317 the Umayyads of Cordova also claimed the Khalifate and used the title, there were three Commanders of the Faithful at one time in the Muslim world. Yet it should be noticed that the constitutional position of these Umayyads was essentially different from that of the Fatimids. To the Fatimids, the Abbasids were usurpers. The Umayyads of Cordova, on the other hand, held, like the Zaydites and some jurisconsults of the highest rank, that, when Muslim countries were so far apart that the authority of the ruler of the one could not make itself felt in the other, it was lawful to have two Imams, each a true Successor of the Prophet. The good of the people of Muhammad demanded it. Still, the unity of the Khalifate is the more regular doctrine. [Sidenote: AL-HAKIM]