After the battle of Nahavand no serious attempt made to reverse the fortunes and drive the Arabs completely out Iran. Although there was local resistance in certain places as the Arabs steadily advanced towards the eastern reaches of the Sasanian empire. The most serious of these was the force of 40,000 men led in Khorasan by the nobleman Qaren shortly after the death of Yazdgerd; however, the Arabs surprised and defeated this force.
Between the early ninth and eleventh centuries there arose Persian principalities and states, mainly in the east, with the vast region of greater Khorasan as their center, except for one major Iranian dynasty, the Buyids, who ruled in the west, center and south, including, for some time, Iraq and Baghdad. Such a development was not planned or consciously designed. Indeed, the dynasties that ruled in this period usually had the nominal approval of the caliph in Baghdad, who himself was often a puppet in the hands of his Turkish generals. The development was a natural consequence of the weakness of the caliphate at center and – as part of this – the growth of regional powers in the east, where genuine as opposed to nominal direct rule was no longer tenable. With Persians increasingly present in the military, administrative and literary spheres of the Abbasid caliphate, and with their involvement in regional government, especially in the east, it was only a matter of time for autonomous or independent powers to rise from their midst...Read more