On the fall of Rei, the Arabs lost no time in turning their arms against all quarters at once of the Persian empire. Six considerable armies, drawn from Kûfa and Bussorah, and continually replenished from Arabia and the provinces by soldiers of fortune thirsting for rapine and renown, invaded as many different regions; and these, as they were overrun, fell each under the government of the leader who reduced it. Thus, one after another, Fars, Kermân, Mokrân, Sejestan, Khorasan, and Azerbâijân, were annexed to the empire of Islam. Some of these, though subordinate in name, had been virtually independent; and so now, even after the heart had ceased to beat, they maintained a dangerous vitality. When tributary and reduced to an outward subjection, the people would ever and again rise in rebellion; and it was long before the Arabs could subside into a settled life, or feel secure away from the protection of garrisoned entrenchments. [Sidenote: Subordinate position of the conquered races.]But the privileges of Islam on the mere confession of the Faith were so considerable and enticing, that the adherents of the Zoroastrian worship were unable to resist the attraction; by degrees the Persian race came over to the dominant creed, and in the end opposition ceased. The notices of Zoroastrian families, and of Fire temples destroyed in after reigns, show indeed that in many quarters the conversion was slow and partial.[392] But after the fall of the Court, the death of Yezdegird, and the extinction of outlying authority, the political and social inducements to join the faith of the conquerors were, for the most part, irresistible. The polished Persian formed a new element in Moslem society. But however noble and refined, he long held a place inferior to, and altogether distinct from, that maintained by the rude but dominant races of Arabian blood. Individuals or families belonging to the subject peoples, on embracing Islam, attached themselves to some Arab chief or clan, as adherents, or ‘clients’ of the same; and in this dependent position could claim some of the privileges of the ruling faith. But neither here nor in other lands did they intermarry with the Arabs on equal terms; they were looked down upon as of an inferior caste. Thus, although in theory, on becoming Mussulmans, the conquered nations thereby entered the equal brotherhood of the Faith, they formed, not the less, a lower estate. The race and language, ancestral dignity, and political privileges, of the Arabs continued to be paramount throughout the empire for many generations. [Sidenote: Miraculous tale connected with the siege of Darâbgird.]