22 A Short History of the Middle East Northern and Southern Arabia respectively; and the Khawarij overran Iraq, Southern Persia, and the greater part of Arabia. As a contemporary poet sang: 'They are split in sects: each province hath its own Commander of the Faithful, each its throne. . . .' Thus the Arab nation was torn asunder by the old tribal preten- sions which Mohammed sought to abolish. That they ultimately proved fatal to the Umayyads is no matter for surprise; the sorely- pressed dynasty was already tottering, its enemies were at its gates. But by good fortune it produced in this crisis an exceptionally able and vigorous ruler, 'Abd ul-Malik (685-705), who not only saved his house from destruction, but re-established its supremacy and gave the Muslim civilization an opportunity to enrich itself cul- turally. His iron-handed governor of Iraq ruthlessly put down the rebellion in the eastern provinces, and for twenty years provided peace and security by his despotic rule. In order to knit together the far-flung empire and curb the separatist tendencies of the provinces Abd ul-Malik borrowed from earlier empires the institution of an official postal system by means of relays of horses; he substituted for the Byzantine and Persian coins, which had hitherto been in general use, new gold and silver pieces on which he caused sentences from the Qur'an to be engraved; and he made Arabic, instead of Greek or Persian, the official language of financial administration.1 This reform does not mean that the non-Arab personnel of the administration, largely Christian by religion in the Levantine provinces, were replaced. But by this time the social barrier which 'Umar had attempted to impose between the Arab garrisons and the non-Arab and non-Muslim majority of the population was beginning to break down. The Arab cantonments had soon grown into towns and cities; Arabs had acquired land; and, as formerly between Alexander's Greeks and Orientals, social contact and intermarriage (for Muslims were permitted to take non-Muslim wives) were doing their levelling work. Moreover, non-Muslims 1 Nicholson, op. cit., 199 ff. It is of interest that, because these coins bore quotations from the Qur'an, the eighth-century founder of one of the four schools of Muslim jurisprudence objected to their being given in payment to non-Muslims. (D. S. Margoliouth, The Early Development of Moham- medanism, 119.)