The Sasanians were the last of the ancient Persian dynasties, and the largest empire to espouse Zoroastrianism, before the encounter with the Arabs swept away the pre-Islamic institutions. Using new sources, Touraj Daryaee provides a portrait of the empire's often negelcted social history, exploring the development of political and administrative institutions from foundation by Ardashir I to the last king, Yasdegerd III, and the attempts of his descendants to re-estabish a second state for almost a century after.