The conception of the Khalifate still exercises a fascinating influence, regarded in the light of a central point of union against the unfaithful. Apart from the _'âmils_, Mohammed's agents amongst the Arabian tribes, the Khalifate was the only political institution which arose out of the necessity of the Moslim community, without foreign influence. It rescued Islâm from threatening destruction, and it led the Faithful to conquest. No wonder that in historic legend the first four occupiers of that leadership, who, from Medina, accomplished such great things, have been glorified into saints, and are held up to all the following generations as examples to put them to shame. In the Omayyads the ancient aristocracy of Mecca came to the helm, and under them, the Mohammedan state was above all, as Wellhausen styled it, "the Arabian Empire." The best khalîfs of this house had the political wisdom to give the governors of the provinces sufficient independence to prevent schism, and to secure to themselves the authority in important matters. The reaction of the non-Arabian converts against the suppression of their own culture by the Arabian conquerors found support in the opposition parties, above all with the Shî'ah. The Abbasids, cleverer politicians than the notoriously unskillful Alids, made use of the Alid propaganda to secure the booty to themselves at the right moment. The means which served the Alids for the establishment only of an invisible dynasty of princes who died as martyrs, enabled the descendants of Mohammed's uncle Abbas to overthrow the Omayyads, and to found their own Khalifate at Bagdad, shining with the brilliance of an Eastern despotism.
When it is said that the Abbasid Khalifate maintained itself from 750 till the Mongol storm in the middle of the thirteenth century, that only refers to external appearance. After a brief success, the actual power of these khalîfs was transferred to the hands, first, of the captains of their bodyguard, then of sultan-dynasties, whose forcibly acquired powers, were legalized by a formal investiture. In the same way the large provinces developed into independent kingdoms, whose rulers considered the nomination-diplomas from Bagdad in the light of mere ornaments. Compared to this irreparable disintegration of the empire, temporary schisms such as the Omayyad Khalifate in Spain, the Fatimid Khalifate in Egypt, and here and there an independent organization of the Khârijites were of little significance.