The Sasanian Empire ruled Iran and Mesopotamia from 224 to 651, and was the eastern Roman empire's equal and rival for four centuries.
The Sasanian Empire ruled Iran, Mesopotamia and much of Central Asia from 224 to 651, and for the whole of that time it was Rome's only true peer.
This distinction matters for how the archive reads it. The Vandals and Ostrogoths were successor kingdoms built inside the Roman world; the Sasanians were an independent empire with their own imperial ideology, state religion and court, and they regarded Rome as an equal rather than a superior.
It ended not through Roman victory but through mutual exhaustion: the great war of 602–628 left both empires so weakened that the Arab conquests took Iran entirely and half of the Roman east with it.
Ardashir I overthrew the last Parthian king, Artabanus IV, around 224, and the dynasty took its name from his ancestor Sasan.
The new regime presented itself as a restoration — a deliberate revival of the Achaemenid empire that Alexander had destroyed — and adopted a far more centralised administration than the Parthians had run.
Its capital was Ctesiphon on the Tigris, which remained the seat of the empire for its whole existence and was among the largest cities in the world.
Zoroastrianism was the state religion, with an organised priesthood and royal fire temples, and the fire altar appears on the reverse of Sasanian coinage throughout the dynasty.
The empire nonetheless contained very large Christian, Jewish and later Manichaean populations. Treatment varied sharply by reign and by the state of relations with Rome — Christians could be tolerated as subjects or suspected as a Roman fifth column depending on the decade.
Society was strongly stratified, with a great noble houses at the top whose power was a permanent constraint on royal authority — and, in 628, the mechanism by which Khosrow II was removed.
War with Rome ran, on and off, for four hundred years, mostly over Armenia and Mesopotamia and mostly without decisive result.
Its most spectacular moment came in 260, when Shapur I defeated and captured the Roman emperor Valerian alive — an event commemorated in rock reliefs at Naqsh-e Rostam and never forgotten on either side.
The wars were generally limited and the frontier generally stable. What made the last war different was that Khosrow II abandoned the traditional objectives and tried to destroy the Roman empire outright.
Ardashir I (224–242) founded the dynasty and its ideology. Shapur I (240–270) fought three Roman emperors and captured one.
Khosrow I Anushirvan (531–579) is the reforming king: he restructured taxation and the army, patronised learning, and gave the empire the administrative shape it held to the end. Byzantine writers treated him as a formidable and civilised opponent.
Khosrow II (590–628) took the empire to its greatest extent and destroyed it in the attempt. Yazdegerd III (632–651) was the last shah, dying a fugitive after the Arab conquest.
The empire was administratively sophisticated, with a professional bureaucracy, a land-tax system reformed under Khosrow I, and a network of royal roads and postal stages.
It sat astride the trade routes between the Mediterranean and India and China, and much of its wealth came from controlling that traffic.
Its art — rock reliefs, silver plate, textiles — was exported and imitated widely, and Sasanian silverwork turns up from Europe to China. The Academy of Gondishapur made it a centre of medicine and learning.