IV.

The Sasanians

In ad 226 Ardashir I, a Persian vassal-king, rebelled against the Parthians, defeated them at the Battle of Hormuz (224), and founded a new Persian dynasty, the Sasanians. He went on to conquer several minor neighbouring kingdoms, invaded India, levying heavy tribute from the rulers of the Punjab, and conquered Armenia. He also established Zoroastrianism as the official religion of Persia. Ardashir was succeeded in 240 by his son Shapur I, who waged two successive wars against the Roman Empire, conquering territories in Mesopotamia and Syria and a large part of Asia Minor. Between 260 and 263 he lost his conquests to Odenathus, the prince of Palmyra, and an ally of Rome. War with Rome was renewed by Narses whose army was virtually annihilated by Roman forces in 297. Narses was compelled to conclude peace terms whereby the western boundary of Persia was moved from the Euphrates River to the Tigris River and much additional territory was lost. Shapur II (reigned 309-379) regained the lost territories, however, in three successive wars against the Romans.

The next ruler of note was Yazdegerd I, who reigned in peace from 399 to 420. Although he initially allowed the Persian Christians freedom of worship and may even have contemplated becoming a Christian himself, he later returned to Zoroastrianism and launched a four-year campaign of ruthless persecution against the Christians. The persecution was continued by his son and successor, Bahram V, who declared war on Rome in 420. The Romans defeated Bahram in 422; by the terms of the peace treaty the Romans promised toleration for the Zoroastrians within the Roman Empire in return for similar treatment of Christians in Persia. In 424, Persian Christians declared their independence from the western Church.

In the late 5th century a new enemy, the barbaric Ephthalites, or “White Huns”, attacked Persia; they defeated the Persian king Firuz II in 483 and for some years thereafter exacted heavy tribute. In the same year Nestorianism became the official doctrine espoused by the Persian Christians. Kavadh I favoured the teachings of Mazdak (fl. 5th century), a Zoroastrian high priest who sought to make property common. In 498 Kavadh was deposed by his orthodox brother Zamasp, but with the help of the Ephthalites, Kavadh was restored to the throne in 501. He fought two inconclusive wars against Rome, and in 523 he withdrew his support for Mazdak and ordered the massacre of his followers. Kavadh's son and successor, Khosrau I, was successful in his wars with the Byzantine emperor Justinian I and extended his sway to the Black Sea and the Caucasus, becoming the most powerful of all the Sasanian kings. He reformed the administration of the empire and restored Zoroastrianism as the state religion. His grandson Khosrau II began a long war against the Byzantine Empire in 602 and by 616 had conquered almost all south-western Asia Minor and Egypt. Further expansion was halted by the Byzantine emperor Heraclius, who between 622 and 627 drove the Persians back within their original borders. The last of the Sasanian kings was Yazdegerd III, during whose reign (632-651) the Arabs invaded Persia, destroyed all resistance, gradually replaced Zoroastrianism with Islam, and incorporated Persia into the caliphate.