first of these was the proud national spirit of the Iranians which was eventually to break down the supremacy of the Arabs and give birth to the first Persian dynasties in Islām. The few wise governors of Khurāsān found in this their strongest support, but, outraged again and again by an arrogant and rapacious administration, the subject peoples became embittered and sought all means of escape from its tyranny. The second was the interest of the commercial relations on which the wealth and prosperity of the country depended. This again might have disposed the cities to accept a rule which promised not only stability, but a wide extension of opportunity. The Arab governors, as we shall see, were not indeed blind to this, but the exactions of the treasury, and still more the greed of local officials, combined with the unsettlement of constant invasion to create an attitude of distrust, which deepened later into despair. It must not be forgotten that the commercial ties of the Sogdians were much stronger with the East than with the West, and that this too prompted them to cultivate relations with the Turks and Chinese rather than with the Arabs when the necessity of making a choice was forced upon them. _The Arabic Sources._ The early Arabic sources are remarkably rich in material for the reconstruction of the conquests in Khurāsān and Transoxania. For the earlier period the narratives of Yaʿqūbī and Balādhurī are nearly as full as those of _T_abarī, but the special value of the latter lies in his method of compilation which renders the traditions amenable to critical study and thus provides a control for all the others. Moreover, while the other historians, regarding the conquests of Qutayba as definitely completing the reduction of Transoxania, provide only meagre notices for the later period, _T_abarī more than compensates for their silence by the enormous wealth of detail embodied in the accounts he quotes from Al-Madāʾinī and others of the last thirty years of Umayyad rule. As a general rule, these three historians rely on different authorities, though all use the earlier histories of Al-Madāʾinī and Abū ʿUbayda to some extent. The monograph of Narshakhī (d. 959 A.D.) based on both Arabic and local sources, with some resemblance to Balādhurī, is unfortunately preserved only in a Persian version of two centuries later which has obviously been edited, to what extent is unknown, but which probably represents the original as unsatisfactorily as Balʿamī’s Persian version of _T_abarī. Even so it preserves to us some account of the peoples against whom the Arab invaders were matched, and thus does a little to remedy the defects of the other historians in this respect. It may well be doubted, however, whether some of its narratives merit the reliance placed upon them by van Vloten[17]. The much later historian Ibn al-Athīr introduces very little new material, but confines himself for