What Was the Persian Royal Road?
The Persian Royal Road was the great imperial highway of the Achaemenid Empire, running roughly 2,700 km from Susa, the administrative capital in lowland Khuzistan, to Sardis, the Lydian capital in western Anatolia. Along the way it had 111 way-stations at intervals of about 25 km, and a courier service that could cover the distance in seven days. The road was the principal artery of imperial communication, the principal corridor of imperial military movement, and the model for every subsequent imperial postal system in Western Asia. The Greek historian Herodotus, who travelled parts of the road in the fifth century BCE, described it in detail (5.52–54), and his account is the central ancient source. The standard modern treatment is Pierre Briant, From Cyrus to Alexander (2002), chapter 11; Tuplin, “Persian Garrisons in Xenophon and Other Sources” (2004), is the technical study.
A note on terminology. The Old Persian name of the Royal Road is not securely attested. Herodotus gives it in Greek; the Achaemenid inscriptions mention imperial roads but do not preserve a single compound name for the Susa–Sardis axis. The Old Persian word for “courier” is debated; the term that recurs in the Achaemenid sources is something like pirradaziš, but specialists disagree.
The building
The Royal Road, as a coordinated system of road building, station construction, and courier organisation, was developed across several Achaemenid reigns. Darius’ principal contribution, around 510 BCE, was the Susa–Sardis axis, which he describes in his inscriptions as a single great project. The road was functioning by the time of the Ionian revolt of 499 BCE, when the Greek cities used it to communicate with one another, and was certainly in use during the Persian expedition of 490 BCE.
The genius of the system was not the invention of new routes. The road followed, in large part, older paths that had carried traffic between Mesopotamia and the Mediterranean for millennia. The Susa–Babylon section followed the caravan road of the Elamite and Babylonian kingdoms. The crossing of the Assyrian heartland followed the old Assyrian imperial roads. The section through the Syrian desert followed the caravan route used by the merchants of Tyre and Sidon. The Achaemenid achievement was the integration of these older routes into a single coordinated system, with standardised stations, a regular courier service, and imperial protection.
The route
The road, as described in detail by Herodotus, ran from Susa in lowland Khuzistan northwestward through the passes of the Zagros mountains to the Median capital Ecbatana, and then westward through the Assyrian heartland to the upper Euphrates, the Cilician Gates, the Halys River, and the Lydian capital Sardis. The total distance by modern measurement is about 2,700 km, depending on the exact route. Herodotus gives the total as 1,675 parasangs of post-stations plus a day’s walk at each end; his arithmetic is sometimes garbled in transmission, and the 2,700 km figure is a reasonable modern estimate.
The principal cities and stations included Susa, Ecbatana, Tigris crossings, the Assyrian capitals of Nineveh and Arbela, the upper Euphrates crossings near Carchemish, the Cilician Gates near Tarsus, the Cilician and Cappadocian highlands, the Halys crossings, the Phrygian capital Gordion, and finally Sardis. Each major city was both a station and a stopping point; the way-stations themselves were the smaller installations between the cities, where couriers could change horses and travellers could find food and shelter.
The way-stations and the courier service
The most distinctive feature of the system was the network of way-stations. Herodotus says the road had 111 way-stations at intervals of about 25 km; modern calculations broadly agree, depending on the assumed length of the stade. Each station was supplied with fresh horses and provisions, maintained at local expense and protected by imperial authority. The couriers, the elite of the imperial postal service, were entitled to use the horses and provisions at each station and were required to deliver messages with great speed. The famous passage in Herodotus — “neither snow, nor rain, nor heat, nor darkness of night” — is specifically a description of the courier service, and Herodotus uses it as ethnography, not as praise.
The system was not merely a postal service in the modern sense. The couriers carried sealed messages from the King of Kings to the satraps, from the satraps to the central government, and from the court to the military and the satrapal treasuries. The messages were sealed with the royal seal. The system allowed the King of Kings to receive intelligence from the far corners of the empire within a matter of days, and to despatch orders to distant satraps with equal speed. Xenophon, in the Anabasis (4.5.10–4.6.4), describes the working of the system in some detail, and the picture he gives is the day-to-day one: the army was fed by the obligation of the satrapy through which it passed to provide a fixed number of days’ supply, and the obligation was the agēlaion.
Why it mattered
The road allowed the rapid movement of armies across the western half of the empire, and gave the Achaemenid kings a strategic depth that the Greek city-states could not match. The army of Darius, in the expedition against the Scythians of 513 BCE, used the road system to move from Sardis toward the Danube. The army of Xerxes I, in 480 BCE, used the same system to move from Sardis to the Hellespont. The road also allowed the rapid movement of reinforcements, the evacuation of wounded soldiers, and the rapid response to revolts along the western frontier.
The road had a political dimension. The satraps of the western provinces were bound to the central government by the constant flow of messages, gifts, and orders that the road carried. The “King’s Eyes and Ears” — the imperial inspectors who toured the empire on a regular schedule — used the road to report on the conduct of the satraps. The system of the Royal Road, the courier service, and the imperial inspectors together formed a system of control that allowed the Achaemenid state to combine centralised strategic direction with local autonomy.
The road had an economic dimension as well. Merchants and travellers used it under imperial protection, and the towns along its length prospered from the transit trade. The road carried the tribute from the satrapies to the central treasuries, and the gifts and luxury goods from the imperial centre to the provincial capitals. The road carried lapis lazuli from Afghanistan, silver from Lydia, textile goods from Babylon, and the incense of Arabia. The Royal Road ended at Sardis; the later caravan routes through Palmyra extended the network further, but the China link was a much later Silk Road phenomenon, not an Achaemenid achievement.
The legacy
The Royal Road became a model for the subsequent postal systems of the Hellenistic, Roman, and Sasanian empires. The Roman cursus publicus, the imperial postal system developed under Augustus, was directly inspired by the Achaemenid precedent. The Sasanian postal service, organised along the rāh system, used way-stations on the major routes, and the English word “post” ultimately derives from this Persian-Latin vocabulary, transmitted through the Sasanian intermediary.
The road was also a major channel for the spread of religions, languages, and ideas across the ancient world. The Zoroastrian priesthood used it to communicate across the empire. The Jewish exiles of Babylon used it to travel to Jerusalem. Christian communities of the first centuries CE used it to maintain contact with Antioch, Rome, and Alexandria. The road was one of the important channels of cultural exchange in the ancient world, and its role in the development of the great Eurasian religious and cultural traditions is real, even if it is sometimes exaggerated.
The Royal Road remains one of the distinctive achievements of Achaemenid imperial administration. The road, the way-stations, the courier service, and the imperial inspectors together formed a system of communication that allowed the Achaemenid kings to rule an empire that stretched from the Aegean to the Indus, and they shaped the history of imperial governance for the next thousand years.
Reading
- Herodotus, The Histories, 5.52–54, with Robin Waterfield translation (1998)
- Briant, Pierre. From Cyrus to Alexander (2002), chapter 11
- Wiesehöfer, Josef. Ancient Persia (1996), pp. 100–105
- Tuplin, Christopher. “Persian Garrisons in Xenophon and Other Sources” in Xenophon and his World (2004)
- Sancisi-Weerdenburg, H. “The Persian Road to the Greek World” in Achaemenid History IV (1990)