half a century later almost independent, and later still a focus of heterodox tendencies.
The further march of events is connected, not with these wars but with Khālid's unparalleled succession of victories, and with the complication on the Syrian border. The subjection of Central Arabia to Medina inspired the Arabs of the border districts with a profound respect, but it simultaneously excited the warlike propensities of the most important tribes of Arabia. It would have been an enormous task for the government in Medina to compel all these restless elements, accustomed to marauding excursions, to live side by side in neighbourly peace under the sanctuary of Islām in unfertile Arabia. Within the boundaries of the empire however such fratricidal feuds were henceforth abolished. It was only to be expected that after the withdrawal of Khālid's army a reaction against Medina should seize upon the newly subjected tribes. The necessity of keeping their own victorious troops employed, as also of reconciling the subjected ones to the new conditions, irresistibly compelled an extension of the Islāmitic rule beyond the borders of Arabia. Chronologically the raid on 'Irāḳ (the ancient Babylonia) stands at the commencement of these enterprises. This however was quite a minor affair, and the main attention of the government was directed to Syria.
Before going further, we have to shew that our exposition differs radically from all the usual descriptions of the expansion of the Arabs, not only in our estimates of the sources and events, but also in our chronological arrangement of them. The conquests of the Saracens have in later years been a focus of scientific debate. Through the labours of De Goeje, Wellhausen and Miednikoff a complete revolution in our views has been effected. We have learnt to differentiate the various schools of tradition, of which that of 'Irāḳ, represented by Saif ibn Omar, has produced an historical novel which can hardly be classed as actual history. The reports of the Medina and the Syrian schools are more trustworthy, and a certain amount of reliance may be placed on the Egyptian school, but they all suffer from later harmonising efforts, and also from their revision during the period of the Abbasids, in which it was sought in every way to depreciate the Umayyads. All these traditions are now being collected and critically sifted in the stupendous annals of Leone Caetani. His epoch-making results are utilised in the following paragraphs.
Between Yamāma and the Ḥīra district, which we must regard as a long, narrow strip of country, the North Arabian (Ishmaelite) tribe of Bakr ibn Wā'il led a nomadic existence on the borders of the cultivated country, covered by the protecting marshes of the lower Euphrates, and this tribe was again subdivided into various independent minor groups. They formed part of the restless border tribes against which Ḥīra had been erected as a bulwark. The sub-tribe of the Banū Shaibān especially
