The Achaemenid Empire: Persia’s First Great Empire (550–330 BCE)

In October 331 BCE, on the broad plain of Gaugamela east of Mosul, the army of Darius III met the army of Alexander of Macedon. Arrian’s Anabasis, our best ancient source, gives 47,000 for Alexander and perhaps 250,000 for Darius; the numbers are inflated in both directions. What is not in dispute is the result: the Persian line broke, Darius fled east, and within two years he was dead, murdered by his own satraps in Bactria. The Achaemenid empire, founded by Cyrus II less than two centuries earlier, was at an end.

The Achaemenid achievement is the central question of this article. It was the largest state the ancient world had then seen, and arguably the largest the world would see until the nineteenth century. It governed a population of perhaps 50 million from the Balkans and the Nile to the Indus, from the Caspian to the Persian Gulf. It lasted 220 years. It did so without the cultural or linguistic assimilation that Roman citizenship eventually required, and it did so while losing every major war it fought with Greece. The puzzle is worth a moment.

The standard modern works are Pierre Briant’s From Cyrus to Alexander (2002), the indispensable English synthesis; Josef Wiesehöfer’s Ancient Persia (1996); Maria Brosius’s The Persian Empire from Cyrus II to Artaxerxes I (2020), with its strong Babylonian evidence; Margaret Cool Root’s The King and Kingship in Achaemenid Art (1979); and Amélie Kuhrt’s The Persian Empire: A Corpus of Sources from the Achaemenid Period (2007), the standard source collection. Matthew Stolper’s work on the Persepolis Fortification Tablets is the most important single body of modern scholarship on the Achaemenid economy.

The Iranian background

The Achaemenid state did not emerge from a vacuum. By the seventh century BCE, the Iranian Plateau supported a network of polities: the Elamite kingdom at Susa, the Mannaeans in the north-west, the Medes in the north-western Zagros with their capital at Ecbatana (modern Hamadan), and a swarm of smaller Iranian and non-Iranian states. The Median kingdom, founded in the eighth century BCE, had been a serious power in its own right. The Medes contributed the administrative practices, the elite warrior culture, and the close ties with the Mesopotamian world that the Achaemenids inherited. The Median capital at Ecbatana became a summer residence of the Achaemenid kings, and the Median language (an old western Iranian tongue) is the ancestor of modern Kurdish.

The Median contribution to the destruction of the Assyrian Empire in 612 BCE, in alliance with the Babylonians, was decisive. Nineveh fell; the Assyrian state collapsed. The Babylonian share of the spoil, the Chaldean kingdom of Nabopolassar and his son Nebuchadnezzar II, dominated Mesopotamia. The Median share was the largest portion of the Iranian Plateau. By 550 BCE the Medes were strong enough to attract the attention of Cyrus II.

Cyrus the Great (559–530 BCE)

Cyrus II succeeded his father Cambyses I as king of Anshan, a small kingdom in Elam, around 559 BCE. Within a decade he had defeated the Median king Astyages (550 BCE), the Lydian king Croesus (c. 547 BCE), and the Babylonian king Nabonidus (539 BCE). The conquests were each, in their way, remarkable; the policy after conquest was more remarkable still.

The Cyrus Cylinder, found at Babylon in 1879 by Hormuzd Rassam and now in the British Museum, presents Cyrus as the chosen of Marduk, liberator of the Babylonian people from the impious Nabonidus, and restorer of the shrines of the gods. The cylinder is a Mesopotamian document, written in the language and idiom of Babylonian kingship. The “first declaration of human rights” reading is a 20th-century construction, popularised in Iran under the Pahlavis and picked up by the United Nations when a replica was displayed in 1971. Modern Assyriologists, including Irving Finkel, treat the cylinder as a piece of Babylonian royal propaganda in a long tradition. Finkel’s recent re-reading (2013) of the cuneiform is the most important modern philological work on the text.

Cyrus died in 530 BCE, campaigning against the Massagetae, a nomadic people beyond the Jaxartes (Syr Darya). The principal source is Herodotus (1.201–214), not Strabo or Berossus, both of whom mention the campaign at second hand. Strabo’s account, in his Geography 11.8, derives from Ctesias, and Ctesias is unreliable. Herodotus tells the story of Tomyris, the Massagetae queen who allegedly put Cyrus’s head in a wineskin full of blood — a literary flourish, not a historical report.

Cyrus’s body was brought back to Pasargadae, where a small stone chamber on a six-stepped platform was built to receive it. The tomb is austere: a single gabled chamber, roughly 11.1 by 7.2 metres, without the elaborate carved reliefs of Persepolis. Alexander the Great reportedly visited it and had it restored; the inscription on the platform, “Passer-by, I am Cyrus, who gave the Persians an empire,” is generally thought to be Hellenistic or later.

Cambyses II and Egypt (530–522 BCE)

Cyrus was succeeded by his son Cambyses II, who reigned from 530 to 522 BCE. The major event was the conquest of Egypt in 525 BCE. The last pharaoh of the Twenty-Sixth Dynasty, Psamtik III, was defeated at the Battle of Pelusium, and Egypt became an Achaemenid satrapy. The conquest brought the Achaemenid state into direct contact with Pharaonic Egypt, with its temples, its priesthoods, and its bureaucratic traditions. Cambyses reportedly adopted elements of Pharaonic titulature and visited the temple of Neith at Sais, though Herodotus portrays him as a sacrilegious tyrant (3.25–38). Modern scholarship treats Herodotus’s image as hostile Greek propaganda, but the reign was troubled: Cambyses was absent from Iran for years, a revolt in Media led by a claimant named Gaumata shook the centre, and Cambyses himself died in 522 BCE. The ancient tradition that he died by his own hand (accidental self-wounding or suicide) is the minority view; the more common ancient account is assassination or accident. Darius’s own version, on the Behistun Inscription, is that Gaumata killed Cambyses.

Darius the Great and the reorganisation of empire (522–486 BCE)

The death of Cambyses triggered a succession crisis resolved by a collateral branch of the Achaemenid house. Darius I, known to history as Darius the Great, was not the direct heir of Cyrus and Cambyses, and his accession was contested by revolts across the empire. He claims to have fought and won nineteen battles in the year following the death of Gaumata. The claim is on the Behistun Inscription, a trilingual text in Old Persian, Elamite, and Babylonian carved about 100 m up the cliff at Behistun in western Iran, on the road between Ecbatana and Babylon.

The Behistun Inscription is among the most important documents of the ancient world. It includes a list of the rebels Darius defeated, an account of how the impostor Gaumata had usurped the throne, and a statement of Darius’s legitimacy as the chosen of Ahura Mazda. The relief shows Darius with his foot on the chest of Gaumata, with nine bound rebel kings before him and the winged figure of Ahura Mazda above. Henry Rawlinson’s copies of the 1830s–1840s were the key to the decipherment of cuneiform. The location, the iconography, and the trilingual text all served the same purpose: to anchor the legitimacy of the new branch of the Achaemenid house in cosmic order and to advertise that legitimacy to every traveller on the great road.

Darius’s reign was a period of administrative innovation. The empire was reorganised into roughly twenty satrapies, each governed by a satrap answerable to the King of Kings. The satrapies paid a fixed tribute, calibrated to their productivity, in gold, silver, or kind. A royal secretary, a garrison commander, and a network of inspectors known as the King’s Eyes and Ears, touring the empire on a regular schedule, kept watch on the satraps. A standard gold coin, the daric, was introduced, struck from Lydian gold at about 8.4 grams and of consistent weight and fineness for more than a century. The Royal Road from Susa to Sardis, roughly 2,700 km with 111 way-stations at intervals of about 25 km, was built (or rather, consolidated from earlier roads) around 510 BCE, with a courier service that could carry a message the length of the road in seven days, according to Herodotus. The great ceremonial complex at Persepolis was begun.

The Achaemenid state’s response to the Greek revolt of the Ionian cities, which began in 499 BCE with the support of Athens and Eretria, was the punitive expedition of 490 BCE. The expedition captured Eretria and then landed at the Bay of Marathon, where the Athenian army under Miltiades defeated the Persian force. Marathon was a serious blow to Persian prestige, but it did not end the war. Darius began planning a larger campaign against Greece, which he did not live to lead. He died in 486 BCE, having reigned for thirty-six years.

Xerxes I and the great invasion (486–465 BCE)

Xerxes I, son of Darius, succeeded his father and ruled from 486 to 465 BCE. The early years of the reign were troubled: an Egyptian revolt in 484 BCE and a Babylonian revolt that required the diversion of the army. By 480 BCE, however, Xerxes was ready to launch the great invasion of Greece that Darius had planned. Herodotus gives the army at 2.6 million men plus a support train. No serious modern historian accepts this; the logistical impossibility is obvious. The consensus estimate, after generations of argument summarised by W. Kendrick Pritchett in The Greek State at War (vol. V, 1991), is somewhere between 60,000 and 200,000 effectives, with most scholars favouring a figure in the lower half of that range.

The invasion culminated in three great battles: Thermopylae, where a small Greek force under Leonidas held the pass for several days before being overwhelmed; Salamis, where the Greek fleet under Themistocles won a decisive naval victory in late summer 480 BCE; and Plataea in 479 BCE, where the Persian land army was defeated by the combined Greek forces under the Spartan regent Pausanias. The strategic outcome was, in the long term, a Greek victory; the Persian presence in the Aegean was rolled back over the next half-century.

The Achaemenid state, however, was not broken. Xerxes withdrew to Susa, continued to rule, and was still putting massive resources into the building programme at Persepolis when he was assassinated in 465 BCE. The Greek victories of 480–479 BCE were real, but they did not mark the end of the Achaemenid state. The empire continued, prosperous and powerful, for another 135 years.

The later Achaemenids (465–330 BCE)

Artaxerxes I, called Longimanus, reigned from 465 to 424 BCE. The Peace of Callias, traditionally dated to 449 BCE, ended the long war with Athens and fixed the frontier of Persian influence in the Aegean at the coast of Asia Minor. The court of Susa became a haven for Greek intellectuals and political exiles, including Themistocles, who was given asylum and revenues from several cities. Artaxerxes also issued decrees, recorded in the books of Ezra and Nehemiah, permitting the Jewish exiles to return to Jerusalem and rebuild the Temple. The Achaemenid policy of religious toleration, which had allowed the Jews to rebuild the temple in the 520s under Darius, continued under Artaxerxes.

The reigns of Darius II (423–404 BCE), Artaxerxes II (404–358 BCE), and Artaxerxes III (358–338 BCE) saw a slow erosion of central authority. The Great Satraps’ Revolt of the 360s BCE, in which several western satraps rose against Artaxerxes II, was eventually suppressed but left the empire exhausted. Artaxerxes III, the last great Achaemenid ruler, reconquered Egypt in 343 BCE and crushed a revolt in Phoenicia with notable brutality. He was succeeded by his son Arses (338–336 BCE), who reigned only two years and was murdered; a collateral branch of the dynasty, Darius III, was then raised to the throne by the eunuch Bagoas.

The fall (336–330 BCE)

The reign of Darius III (336–330 BCE) was the final chapter of the Achaemenid state. Darius was a man of considerable personal courage but he inherited a state already in crisis. The army was a patchwork of mercenaries and conscripts, the western satraps were unreliable, and a new power had risen in the northern Aegean: Macedonia, under Philip II, who had unified the Greek city-states and was preparing an invasion of Asia. The assassination of Philip in 336 BCE gave the Achaemenid state a brief respite. The accession of Alexander in 336 BCE brought a more formidable opponent to the Macedonian throne.

Alexander crossed the Hellespont in 334 BCE with an army of about 47,000 infantry and 5,000 cavalry. He met the first Persian satraps at the Granicus River, near Troy, and won a hard-fought victory that opened western Asia Minor. The Ionian Greek cities, long restive under Persian rule, generally welcomed him as a liberator. Memnon of Rhodes, the brilliant Greek mercenary commander in Persian service, proposed a strategy of avoiding pitched battles and devastating the Macedonian supply lines that might have brought the invasion to a halt, but his unexpected death in 333 BCE removed the most dangerous opponent Alexander ever faced. The way was open to the Phoenician coast, Syria, and the great battle of Issus, where Darius III, having taken personal command, was defeated and forced to flee, leaving his family in Alexander’s hands. A second battle at Gaugamela in 331 BCE shattered the last major Persian army. Alexander entered Babylon, Susa, and Persepolis in quick succession. In early 330 BCE, Persepolis was burned, in circumstances that have been debated since antiquity. Later in 330 BCE, Darius III, fleeing east, was murdered by his own satraps in Bactria. Bessus, one of the murderers, was himself of Achaemenid blood, so the dynastic line did not in fact go extinct; but Bessus’s claim was not recognised, and the empire he briefly headed fell in 329 BCE. Darius III was, in any practical sense, the last king of the main Achaemenid line.

Persepolis and the Achaemenid capital system

The Achaemenid capital system, distributed across Pasargadae, Persepolis, Susa, Ecbatana, and Babylon, was itself an expression of the multi-ethnic character of the empire. Pasargadae was the dynastic sanctuary, Persepolis the ceremonial centre, Susa the administrative capital, Ecbatana the summer residence, Babylon the Mesopotamian seat. Of these, Persepolis is the best preserved. Founded by Darius I and expanded by Xerxes and Artaxerxes I, the Persepolis complex includes the great hypostyle hall called the Apadana, the Gate of All Nations, the Throne Hall, the Treasury, and a series of rock-cut royal tombs carved into the mountain behind the terrace.

The Apadana reliefs, carved on the great staircase leading up to the columned hall, depict processions of tribute-bearing delegations from twenty-three subject peoples, each identified by costume and gift, approaching the enthroned king. The visual language, with its blend of Median, Persian, Mesopotamian, and Egyptian elements, is the most fully developed statement of Achaemenid imperial art. The site was also the locus of major Achaemenid festivals, including Nowruz, the New Year celebrated at the spring equinox. Persepolis was burned in 330 BCE by Alexander the Great, in circumstances that have been debated since antiquity. Plutarch’s account (Alexander 38) attributes the burning to a drunken decision by Alexander, encouraged by the Athenian courtesan Thais, after a successful banquet. The truth is unrecoverable.

The satrapy system

The genius of Achaemenid governance lay in the satrapy system, the division of the empire into roughly twenty provinces, each under a satrap answerable to the King of Kings. The system allowed the empire to combine centralised strategic direction with local autonomy in a way that no contemporary state could match. The satraps were drawn from the Iranian nobility and from the Achaemenid clan, but they were required to defer to the King of Kings in matters of war and foreign policy, and they were subject to a layered system of control: a royal secretary who kept the king informed of every order issued in the province, a garrison commander who held the local military independent of the satrap, and the network of inspectors known as the King’s Eyes and Ears.

The tribute system, assessed in Babylonian talents, was collected by a separate royal financial officer, not by the satrap, which was intended to prevent the kind of corruption that had plagued earlier Near Eastern empires. Each satrapy was required to supply a contingent to the imperial army, drawn from its own population and led by its own officers. The Immortals, an elite force of perhaps a thousand men (Herodotus’ “ten thousand” is a Greek literary exaggeration; see Maria Brosius’s discussion in The Persian Empire from Cyrus II to Artaxerxes I), were kept up to strength by immediate replacement of any loss.

The Royal Road and imperial communications

The Royal Road from Susa to Sardis, built or consolidated by Darius I around 510 BCE, was a logistical system held together by a courier service and protected inns. Herodotus (5.52–54) says a message could travel the length of the road in seven days, and on this figure he is closer to believable than on troop numbers. The road was a strategic corridor that bound the western and eastern halves of the empire together, allowed the rapid movement of armies, and facilitated the transmission of imperial decrees in standardised Aramaic. The Roman cursus publicus and the Mongol yam were descendants of this system. The road also played a role in the transmission of religions: the Zoroastrian priesthood, the Jewish community of the exile, the cult of Mithra, and the early Christian communities all used the road and the inns that lined it.

The military

The Achaemenid army was, like the empire itself, a multi-ethnic force. The Persians provided the heavy cavalry core. The Medes, Bactrians, Sogdians, Indians, and Saka provided cavalry contingents of various kinds. The Babylonians, Assyrians, Egyptians, and Jews supplied infantry. The Lydians, Cappadocians, and Phrygians contributed heavily armed lancers. The Arabians and Ethiopians supplied camel corps and archers. Each contingent fought in its own national style, commanded by its own officers, and equipped with the weapons and armour most suited to its terrain.

The Persian cavalry tradition went back to the second millennium BCE. The Median contribution to the destruction of Assyria in 612 BCE was largely cavalry, and the Persian mounted warrior — typically a horse archer armed with bow, light spear, and short sword — was a recurring figure in Achaemenid art. The Achaemenid reliefs at Persepolis and the glazed bricks of Susa show this rider repeatedly: long cloak, quiver, sometimes a tasselled fillet on the brow. The full article on Persian cavalry traces this tradition from Cyrus to Khosrow II.

The Achaemenid navy was equally cosmopolitan. The empire inherited the Phoenician, Ionian, and Egyptian fleets, and the Achaemenid kings used them to project power into the Aegean, the Red Sea, and the Persian Gulf. Darius’s Red Sea canal, which linked the Nile to the Red Sea, was one of the great engineering works of the ancient world.

Religion and culture

The Achaemenid state was, by ancient standards, strikingly tolerant in matters of religion. Cyrus’s cylinder proclaimed his devotion to Marduk in Babylon and Ahura Mazda in Persia; Darius, in his inscriptions, attributed his victories to Ahura Mazda but allowed the Egyptians to worship in their traditional temples and the Jews to rebuild their Temple in Jerusalem. The policy of accommodation was both a moral commitment and a practical tool of imperial governance: by respecting local cults, the kings tied the priesthoods of every nation to the Achaemenid order and made rebellion a religious as well as a political crime.

The Persian religion of the Achaemenid kings was a synthesis of older Iranian, Median, and Elamite beliefs. The supreme god was Ahura Mazda, the Wise Lord, the creator of the world and the patron of truth, justice, and kingship. Below him stood a hierarchy of divine beings, the yazatas, who were the guardians of fire, water, earth, and the social order. The relationship of the Achaemenid royal religion to the Zoroastrian tradition described in the Avesta, and to the religion of the Magi described by Herodotus, is one of the central questions in Achaemenid studies. What is certain is that the Achaemenid kings saw themselves as ruling under the protection of Ahura Mazda, and that they presented their wars as wars of truth against the lie, arta against drug.

Economy, trade, and coinage

The Achaemenid state presided over the most productive economy of the ancient world in territorial terms, combining the agricultural heartlands The empire included the agricultural heartlands of Mesopotamia, the Nile Valley, and the Indus basin, the silver mines of Lydia, the gold and lapis lazuli of Afghanistan, the timber of Lebanon, the textile centres of Egypt, and the incense routes of southern Arabia. The Royal Road, the Red Sea canal, and the Persian Gulf ports allowed the products of these regions to be exchanged on a scale that no previous state had achieved.

The introduction of the gold daric by Darius I, struck from pure Lydian gold at about 8.4 grams, gave the Achaemenid economy a monetary backbone that complemented the older system of bullion and tribute in kind. Silver coinage, in the form of the sigloi, was also struck. The two together provided a flexible medium of exchange that facilitated long-distance trade. The daric circulated widely across the empire and beyond, and remained stable in weight and fineness for more than a century.

The Persepolis Fortification Tablets, which record the movement of grain, sheep, wine, and other goods in the Persepolis economy in the late sixth and early fifth centuries BCE, give a vivid picture of a complex, monetised, and partly market-oriented economy in which long-distance trade, local agriculture, and state taxation were closely intertwined. The Aramaic documents of Elephantine in Egypt, the Achaemenid papyri from the Judean desert, and the Babylonian cuneiform tablets from the Murašû archive in Nippur confirm the picture.

The Achaemenid legacy

The Achaemenid empire left a deep imprint on the subsequent history of the ancient and modern world. Its model of a multi-ethnic, religiously tolerant, administratively sophisticated state influenced the Hellenistic kingdoms, the Roman Empire, the caliphs of Islam, the Byzantine emperors, the Mughal shahs of India, and modern attempts to construct a multi-ethnic state in the Middle East. Pierre Briant’s argument, in the second volume of his history, that the Achaemenid state was a more credible model for the modern world than the Hellenistic city-state is now widely accepted.

The Achaemenid legacy is visible in the surviving Iranian world. The Persian New Year, Nowruz, which was celebrated at Persepolis in Achaemenid times, remains a public holiday in Iran, Afghanistan, Tajikistan, and Azerbaijan. The Achaemenid titles, including shāh, shāhān shāh, and farr, have been carried by Iranian and Persianate rulers into the twentieth century. The ruins of Persepolis, the tomb of Cyrus at Pasargadae, the rock-cut tombs of Naqsh-e Rostam, and the Behistun Inscription remain central monuments of the Iranian national heritage.

The administrative vocabulary of the Achaemenids has been equally durable. The word satrap passed into Greek and from Greek into European languages, where it still means an obsequious provincial official — though the original Achaemenid intention was more subtle: the satrap was a partner of the King of Kings, not merely his agent. The Persian road, the Persian courier, the Persian standard of coinage, and the Persian policy of religious toleration became stock elements in the repertoire of imperial governance.

The visual language of Achaemenid power — the throne of the King of Kings, the robes of the royal couple, the iconography of the investiture relief, the winged disk of Ahura Mazda — was studied and imitated by the Hellenistic successor states, the Parthians, the Sasanians, and the caliphs of Islam. The Persepolis reliefs, the rock-cut tombs of Naqsh-e Rostam, and the tomb of Cyrus defined an Iranian visual vocabulary of kingship that was alive in the Sasanian rock reliefs of Taq-e Bostan and is still visible in the ceremonial architecture of the Islamic Republic of Iran.

A note on dating

A small note on chronology, because the Achaemenid dates in the older literature are still in use and are sometimes confusing. All dates in this article are BCE. The Cyrus Cylinder is dated to 539 BCE on the basis of the Babylonian Chronicle, the Behistun Inscription to c. 520 BCE on stylistic and orthographic grounds, the foundation of Persepolis to c. 518 BCE on the Persepolis Fortification Tablets. The reign of Darius I is conventionally given as 522–486 BCE; the reign of Xerxes as 486–465 BCE; the reign of Artaxerxes I as 465–424 BCE. The “nineteen battles” of Darius are dated to the year 521–520 BCE. The dates of Cambyses’ reign, the Ionian Revolt, Marathon, Salamis, and Plataea are all well established and have not changed substantially since the work of the 19th-century chronologers. The date of Alexander’s crossing of the Hellespont, 334 BCE, is fixed by the Greek sources. The death of Darius III, in the summer of 330 BCE, is fixed by Arrian and Quintus Curtius.

The Achaemenid Empire was, in the judgment of modern historians, the moment at which the ancient world first became a single, connected system. It was also the first of three Persian imperial experiments, each built on the ruins of the last and each contributing something distinctive to the long Persian political tradition. The Parthian and Sasanian pillars of this site take up the second and third of those experiments.