the conquest of Mesopotamia. The expedition, begun from Syria as a starting-point, was completed from 'Irāḳ by the capture of Mauṣil (Mosul) (641).
A systematic conquest of this description was especially called for in regard to 'Irāḳ; for this province could not be regarded as secure as long as its recovery might be attempted. And at this juncture a strong reaction against the Arabs actually set in. The opposition which the Baṣrīs in Khūzistān met with, and which only ceased on the conquest of Tustar (641), was probably in connexion with the activity of the fleeing Yezdegerd and his followers, who summoned the whole of the Iranians to battle against the Arabs. The Baṣrīs troops from Kūfa had already co-operated systematically in Khūzistān, and similar tactics followed now on Persian soil, where the decisive battle was fought in the year 641 at Nihāwand in the neighbourhood of the ancient Ekbatana. The Arabs gained a great victory; the dense garland of praise which legendary lore has woven around it shews how much depended for the Muslims on this victory. But even after this victory the Arabs were not yet masters of the great Median towns, as Hamadhān, Rayy and Ispahān; these were but slowly conquered during the next few years. Here in fact, where they were not greeted as deliverers by kindred Semites, the Arabs had to withstand a stubborn national opposition. Yezdegerd himself certainly caused them no difficulties; after the battle of Nihāwand he had fled further and further away and had finally gone from Istakhr to Marw in Khorāsān. His satrap there was too narrow-minded to support his fallen superior, and in fact he treated him as an enemy, and in 651-652 the deserted and unfortunate potentate appears to have been assassinated.
The Arabs did not reach Khorāsān until the province of Fārs, the actual Persia, was conquered. Fārs could be reached most conveniently from the Persian Gulf. This expedition had therefore been undertaken, with Baḥrain as starting-point, soon after the battle of Ḳādisīya. This made the third base of attack, together with Ctesiphon (Kūfa) and Baṣra, from which the Arabs pushed forward into Iran. Later on the conduct of this expedition passed into the hands of the troops coming from Baṣra. But also in Fārs the same stubborn resistance was met with, which was not broken till after the conquest of Istakhr in the year 649-650 by 'Abdallāh ibn 'Āmir. Following this up 'Abdallāh, especially assisted by the Tamīm and Bakr tribes, began in the following year an advance, the first successful one, towards Khorāsān. This first and incomplete conquest of Persia took therefore more than ten years, whilst Syria and 'Irāḳ fell in an astonishingly short time into the hands of the Arabs. In Persia Arabianism has never become national, and, whilst a few centuries later the other countries spoke the Arabian tongue, the Persian vernacular and the national traditions were still maintained in Persia. The religion of Islām moreover underwent later in Persia a
