Despite the competition it posed to the Romans’ eastern empire and the longevity it enjoyed compared to its Iranian predecessors, English-language histories of the Sassanian Empire are few and far between. In The Last Empire of Iran
(Gorgias Press, 2020), Michael R. Jackson Bonner fills this gap with a work that surveys the empire’s history from its rise in the 3rd century CE to its conquest by Muslim invaders in the 650s. To Bonner, a key reason for the empire’s longevity was the degree of centralization of its government, which was far greater than that of its Parthian predecessors. Thanks to that centralized control and the access to resources that it afforded them, the Sassanians were able to deal with the various challenges their empire faced on its many frontiers, from Roman legions to assaults from Central Asian nomads. Thanks to their effective administration and their military effectiveness, the Sassanians not only persevered against these threats but they succeeded in driving the Roman frontier back westward in the early 7th century, though the extended struggle and the civil war that followed left the Sassanians too weak to face the challenge that arose from the Arabian peninsula just a few years later.