Iran remained part of the ʿAbbasid Caliphate until it fell in 1258, but from the ninth century on a number of emirates arose across the Iranian cultural sphere. Some of these emirates–like the Buyids and Ziyarids–experimented with expressions of political power that hearkened back to the Sasanians, the pre-Islamic empire in Iran. Major changes were afoot, though. From the eleventh century on, three successive invasions swept from the east across the Iranian plateau: (1) the Turkic Seljuks in the eleventh century; (2) the Mongols in the thirteenth century; and (3) the Timurids in the fifteenth century.
Medieval Islamic History 