Iran, despite its conquest by the armies of Islam, retained its own Persian language and much of its culture. Khodadad Rezakhani examines the process by which a Zoroastrian empire became part of the Islamic world.
The Sasanian Empire, which ruled the vast region between the Oxus and Euphrates rivers from AD 223 to 651, was perhaps the most influential of all ancient Iranian empires. Neighbouring Rome in the west, the Chinese empire in the east and in direct relations with the nomadic states of the Eurasian steppe, it was called one of the ‘Two Eyes of the World’. Its territories included ancient centres of civilisation, such as Sumer, Babylon, Elam and Persia. An empire that stopped Roman advancements in the Near East, controlled the Caucasus passage and secured and subdued Central Asia, it was also a centre of culture, from its magnificent architecture to metal and glassworks and fine textiles, whose heritage was apparent in both the medieval European world and within the Islamic civilisation that came to dominate its territories. In religion and learning, too, the culture of Middle Persian literature provided the backbone of the medieval Persianate culture that came to supremacy in the area between India and the Balkans. Zoroastrianism, an ancient religion that influenced both Christianity and Judaism, as well as Manichaeism, the gnostic religion which was at one point the faith of Augustine, originated and flourished in the Sasanian domains.