The Sasanian Empire

Sasanian kingship was theatrical, sacral and deliberately archaising. Ardashir I, having overthrown his Parthian overlord, presented the new dynasty as restoring a legitimate Persian order that the Greeks and Parthians had interrupted, and carved the claim into the cliffs at Naqsh-e Rostam, directly beneath the tombs of the Achaemenid kings.

The šāhānšāh, King of Kings, ruled through a court of great formality. The king sat enthroned behind a curtain, was approached with prescribed gestures, and was surrounded by a hierarchy of offices whose titles and precedence were fixed. Byzantine ceremonial borrowed heavily from it, and so, later, did the Abbasid caliphate.

Administration was more centralised than the Parthian system it replaced, though real power was always negotiated with the great noble houses, whose landholdings and private forces made them indispensable and dangerous. The reforms attributed to Khosrow I in the sixth century were designed to reduce that dependence. They reorganised the tax system around land survey and fixed assessment rather than variable shares of the crop, and created a salaried cavalry class dependent on the crown.

Law was inseparable from religion. Zoroastrian priests administered a legal system whose surviving Pahlavi texts, particularly the Book of a Thousand Judgements, deal in enormous detail with property, marriage, inheritance and family, including arrangements for continuing a lineage that are unusual among ancient legal systems and that later Islamic jurists found deeply objectionable.

The Sasanian army was built around the savaran, heavy cavalry in laminated and mail armour on armoured horses. This was the cataphract, ancestor of the medieval knight in both equipment and social position. Persian nobles served as armoured horsemen because that was what their status required and their estates funded.

Persia also solved a problem the Parthians never had, siegecraft. Sasanian armies took fortified cities routinely, using rams, mines and towers. At Dura-Europos a tunnel assault left defenders and attackers dead underground, and excavation found a Persian soldier’s remains alongside evidence of what may be the earliest attested chemical weapon, sulphur and bitumen burned to produce toxic gas.

The frontiers were plural, and the eastern one was often the more dangerous. The Gorgan Wall, nearly two hundred kilometres of fired brick with forts at intervals, is longer than Hadrian’s Wall and was built to hold a steppe frontier. It is among the largest defensive works of the ancient world and was almost unknown outside specialist scholarship until recently. The Hephthalites in the east killed one Sasanian king and forced another to pay tribute.

The final war with Byzantium is the hinge of late antiquity. Khosrow II took Syria, Egypt and Jerusalem, carried off the True Cross, and besieged Constantinople in 626. Heraclius struck at the Persian heartland instead of defending, Khosrow was deposed and killed, and both empires emerged bankrupt, plague-thinned and militarily spent, a decade before the Arab armies arrived.

The Sasanian economy rested on the irrigated agriculture of Mesopotamia, which under Sasanian management reached a level of productivity it would not see again for centuries. Canal networks in the Diyala plains and southern Iraq were extended and maintained by the state, and the tax revenue from that alluvium funded the empire.

Its position was the other asset. Persia sat astride the land routes between the Mediterranean and India and China, and took a cut of everything moving along them, silk in particular, which Byzantium wanted badly and could only obtain through Persian intermediaries at Persian prices. Byzantine attempts to bypass this, through Red Sea routes and Ethiopian allies, were a persistent theme of sixth-century diplomacy.

Persian Gulf trade linked Mesopotamia to India and East Africa directly, with Sasanian merchants and Sasanian coinage reaching Sri Lanka and beyond. The silver drachm was struck to a consistent standard for four centuries and circulated far outside the empire, and its distribution maps commercial reach better than any text.

The vulnerability was the same as the strength. An economy dependent on irrigation works requires continuous state investment, and the flooding and canal collapse of the early seventh century, coming after decades of war and plague, did damage the empire had no reserves left to repair.

Sasanian society was formally divided into four orders: priests, warriors, scribes and administrators, and the productive commons of farmers and artisans. The texts present the scheme as divinely ordained and socially fixed. How rigid it was in practice is debated, but the ideology of fixed station was pronounced and is one of the things Islamic-era writers remembered about it.

That rigidity produced the most radical social movement of late antiquity. The Mazdakites, in the late fifth and early sixth centuries, preached a redistribution of wealth and, according to hostile sources, of women, and gained enough traction that King Kavad I appears to have supported them, possibly as leverage against the nobility. The movement was crushed with great violence under Khosrow I. It is the closest thing to a social revolution anywhere in the Archives.

Women’s position varied sharply by class and is documented unusually well in the legal texts, which deal with marriage contracts, property, guardianship and divorce in detail. Two women, Boran and Azarmidokht, ruled as queens in the dynasty’s chaotic final years.

Ctesiphon, the capital on the Tigris, was among the largest cities in the world. It was a complex of settlements rather than a single walled city, cosmopolitan, and home to large Jewish and Christian populations alongside Zoroastrians. The Babylonian Talmud was compiled under Sasanian rule.

Zoroastrianism became a state religion under the Sasanians in a way it had not been under the Achaemenids, with an organised priesthood, fire temples supported by endowment, a canon assembled from oral tradition, and an interest in orthodoxy that earlier Iranian religion had not shown.

The architect of that establishment was the priest Kartir, who served four kings and had his own career inscribed on the rock at Naqsh-e Rostam, a rare privilege for anyone outside the royal family, listing the fires he founded and the heretics he suppressed. His inscriptions name Jews, Christians, Buddhists, Brahmins and Manichaeans among those he acted against.

Mani is the most consequential figure. A third-century prophet who taught a dualist cosmology of light and darkness synthesising Zoroastrian, Christian and Buddhist elements, he enjoyed royal favour under Shapur I and was executed under Bahram I. Manichaeism spread west from Iran to North Africa, where Augustine was a Manichaean for nine years, and east as far as China, where it survived for centuries.

Treatment of minorities was inconsistent and political rather than principled. Christians were persecuted when Rome was Christian and Persia was at war with it, and tolerated once the Church of the East established itself as an independent body owing nothing to Constantinople. After that Persian Christianity flourished and sent missionaries to India and China.

Sasanian architecture solved a problem that had defeated its predecessors, how to roof a large square space in brick without timber. The answer was the squinch, an arch across each corner that converts a square to an octagon and then to a circle, allowing domes over square chambers. The technique passed into Islamic, Byzantine and European building.

The signature form is the iwan, a vaulted hall open at one end, and the greatest surviving example is the Taq Kasra at Ctesiphon, a parabolic brick vault spanning some twenty-five metres and rising over thirty, built without centring and still standing after fourteen centuries.

Rock relief was the medium of dynastic statement. At Naqsh-e Rostam, Bishapur and elsewhere, Sasanian kings carved investiture scenes and victories into cliffs. The most famous shows Shapur I with the Roman emperor Valerian kneeling before him, a monument to the only occasion a Roman emperor was captured alive in battle.

Sasanian silver is the luxury art that travelled furthest. Gilded plates showing the king hunting, made in quantity as diplomatic gifts, have been found from western Europe to Siberia and China, and their imagery of the mounted royal hunter shaped Islamic, Byzantine and Central Asian court art for centuries afterwards.

The Sasanians ran a deliberate programme of knowledge acquisition, and it is the direct ancestor of the Abbasid translation movement. Khosrow I in particular sponsored the translation of Greek and Indian works into Middle Persian, and the ideology behind it held that the ancient sciences had been scattered by Alexander and that a legitimate Persian king was obliged to gather them back, a doctrine the Abbasids inherited wholesale.

The Academy of Gondishapur is the institution that carries the reputation, and it needs handling carefully. Later Islamic tradition credits it with a great hospital, a medical school and a teaching tradition combining Greek, Indian and Persian medicine. The contemporary evidence is thinner than the legend, and modern scholarship has scaled the claims back considerably. Something significant probably happened there, but it has not been shown to be a university in the later sense.

Writing was in Pahlavi, a script derived from Aramaic with an awkward peculiarity. Many words were written as Aramaic logograms and read aloud as Persian, so the written and spoken forms diverged sharply. Literacy was correspondingly restricted to a professional scribal class.

The intellectual production that mattered most was religious and literary. The Avesta was committed to writing in a purpose-designed alphabet after centuries of oral transmission, and the Persian royal historical tradition, the Khwaday-Namag, passed into Islamic historiography and eventually became Ferdowsi’s Shahnameh.

The Sasanian source problem is severe and structural. The empire produced court histories and religious literature, and almost none of it survives in its original form. Pahlavi texts were transmitted selectively by a shrinking Zoroastrian community, and the royal chronicles are lost as such.

So the narrative comes from outsiders: Roman and Byzantine historians, above all Ammianus Marcellinus and Procopius, both of whom knew Persia through war; Armenian and Syriac Christian writers, whose interests are ecclesiastical and whose relationship with the Sasanian state was fraught; and Arabic and Persian historians of the Islamic period, writing centuries later from a tradition that had been reshaped.

The compensating evidence is material and epigraphic: royal rock inscriptions in Middle Persian, Parthian and Greek; Kartir’s priestly inscriptions; seals and sealings in enormous numbers, which document administrative structure; coinage, dated and consistent, giving a reliable dynastic skeleton; and the archaeology of the Gorgan Wall, the canal systems and Ctesiphon.

The historiographical shift of recent decades matters here. Sasanian Iran used to be treated as background to Roman history, a hostile frontier rather than a civilisation. Current scholarship treats late antiquity as a shared world of two comparable empires and reads Persia on its own terms, with the consequence that a great deal of what was confidently said fifty years ago is now considered a Roman perspective mistaken for a fact.