*Decline and Fall of the Sasanian Empire* has already been praised as one of the most intellectually exciting books about ancient Persia to have been published for years. It proposes a convincing contemporary answer answer to an ages-old mystery and conundrum: why, in the seventh century CE, did the seemingly powerful and secure Sasanian empire of Persia succumb so quickly and disastrously to the all-conquering Arab armies of Islam? Offering an impressive appraisal of the Sasanians’ nemesis at the hands of the Arab forces which scythed all before them, the author suggests a bold solution to the enigma. On the face of it, the collapse of the Sasanians–given their strength and imperial power in the earlier part of the century–looks startling and inexplicable. But Professor Pourshariati explains their fall in terms of an earlier corrosion and decline, and as a result of their own internal weaknesses. The decentralized dynastic system of the Sasanian empire, whose backbone was a Sasanian-Parthian alliance, contained the seeds of its own destruction. This confederacy soon became unstable, and its degeneration sealed the fate of a doomed dynasty.