The Shî'ah outside Arabia, whose adherents used to be persecuted by the official authorities, not without good cause, became the receptacle of all the revolutionary and heterodox ideas maintained by the converted peoples. Alongside of the _visible_ political history of Islâm of the first centuries, these circles built up their evolution of the _unseen_ community, the only true one, guided by the Holy Family, and the reality was to them a continuous denial of the postulates of religion. Their first _imâm_ or successor of the Prophet was Alî, whose divine right had been unjustly denied by the three usurpers, Abu Bakr, Omar, and Othmân, and who had exercised actual authority for a few years in constant strife with Khârijites and Omayyads. The efforts of his legitimate successors to assert their authority were constantly drowned in blood; until, at last, there were no more candidates for the dangerous office. This prosaic fact was converted by the adherents of the House of Mohammed into the romance, that the last _imâm_ of a line of _seven_ according to some, and _twelve_ according to others, had disappeared in a mysterious way, to return at the end of days as Mahdî, the Guided One, who should restore the political order which had been disturbed ever since Mohammed's death. Until his reappearance there is nothing left for the community to do but to await his advent, under the guidance of their secular rulers (e.g., the shâhs of Persia) and enlightened by their authoritative scholars (_mujtahids_), who explain faith and law to them from the tradition of the Sacred Family. The great majority of Mohammedans, as they do not accept this legitimist theory, are counted by the Shî'ah outside Arabia as unclean heretics, if not as unbelievers. At the beginning of the fifteenth century this Shî'ah found its political centre in Persia, and opposed itself fanatically to the Sultan of Turkey, who at about the same time came to stand at the head of orthodox Islâm. All differences of doctrine were now sharpened and embittered by political passion, and the efforts of single enlightened princes or scholars to induce the various peoples to extend to each other, across the political barriers, the hand of brotherhood in the principles of faith, all failed. It is only in the last few years that the general political distress of Islâm has inclined the estranged relatives towards reconciliation.