Royal Road of Persia: Darius's Highway from Sardis to Susa

The Royal Road of Persia was the most famous highway of the Achaemenid Persian Empire, running some 2,500 kilometres from Sardis in western Anatolia to Susa in southwestern Iran. Organised under Darius I around 500 BC and described by the Greek historian Herodotus, it was lined with official way stations and served by relay couriers. Together with the empire’s other roads, it helped hold together a state that stretched from the Aegean to the Indus.

Background: governing a vast empire

By the late 6th century BC the Persian Empire was the largest the world had seen. Its kings needed to send orders to distant provinces, collect reports from governors (satraps), move troops and receive gifts and tribute. Messages had to travel across mountains, deserts and great rivers.

Earlier empires had built roads: the Assyrians maintained routes with posting stations, and Anatolian kingdoms had their own tracks. The Persians took over and extended these. Darius I, who reorganised the empire’s provinces and taxes after taking power in 522 BC, is generally credited with turning them into a coordinated system of royal roads.

The route described by Herodotus

The fullest description comes from Herodotus, writing around 430 BC. In Book 5 of his Histories he tells how Aristagoras of Miletus, seeking Spartan help for the Ionian Revolt of 499 BC, showed King Cleomenes a bronze map and described the road to Susa. The Spartan king was shocked to learn that the journey took three months.

Herodotus says there were royal stations and excellent inns all along the road, which passed through inhabited and safe country. He lists the regions it crossed: Lydia and Phrygia, the crossing of the Halys River, guarded by gates and a fort, then Cappadocia, Cilicia, Armenia, Matiene and finally Cissia, the land around Susa. Several large rivers, including the Euphrates and the Tigris, had to be crossed by ferry.

In total, Herodotus counts 111 stations and 450 parasangs. A parasang was a Persian measure of distance, roughly what could be walked in an hour, often reckoned at 5 to 6 kilometres. At 150 stades a day, he calculates, the journey took 90 days. The road continued beyond Susa to Persepolis and was linked to other routes leading to Babylon, Ecbatana, Bactria, India and Egypt.

The courier system

The road’s most admired feature was its courier service, which the Greeks knew by the Persian-derived word angaros. Herodotus, in Book 8, explains that riders and horses were posted at intervals of one day’s journey. Each rider carried a message to the next station and handed it on, like a relay race. He compared it to the Greek torch race in honour of Hephaestus.

Herodotus famously wrote that nothing travelled faster than these messengers, and that neither snow nor rain, heat nor night prevented them from completing their stage. Estimates of their speed vary, but a message could probably cross from Sardis to Susa in about one to two weeks rather than three months. Fire signals and shouted relays may also have been used for urgent news, although the ancient evidence for these is thinner.

Evidence from the Persepolis tablets

Herodotus’s account is confirmed and enriched by documents from Persepolis. The Persepolis Fortification Tablets, an archive of clay tablets in Elamite from about 509 to 494 BC, include thousands of records of rations issued to travellers.

These travellers carried a sealed document, called halmi in Elamite, issued by the king or a senior official. At each station they showed it and received flour, beer or wine, and fodder for their animals. The tablets mention travellers going to and from places as distant as Sardis, Egypt, Arachosia (in modern Afghanistan) and India, along with guides, express messengers and groups of workers. They show a road network carefully managed by royal administrators.

Armies, officials and travellers

The road was not only for messages. Satraps travelled along it to report to the king, tax collectors and inspectors moved between provinces, and royal guests and foreign envoys were escorted along it with travel documents. Because the stations were controlled by royal officials, the road also served as a means of surveillance: anyone travelling without authorisation could be stopped at the guarded crossings and gates.

Armies used the same routes. In 498 BC Ionian rebels marched up from the coast and burned Sardis, the road’s western end, provoking a Persian counter-offensive. Xerxes I gathered his army in Cappadocia and moved it west to Sardis before invading Greece in 480 BC. In 401 BC the Persian prince Cyrus the Younger led an army, including more than 10,000 Greek mercenaries, from Sardis towards Babylon in his bid for the throne.

The Athenian soldier Xenophon, who marched with Cyrus, recorded the journey in his Anabasis stage by stage, counting distances in stathmoi (day’s marches or stations) and parasangs, just as Persian administrators did. His account is one of the best guides to how travel across the empire was measured in practice.

What the road was like

The Royal Road was not a paved Roman-style highway along most of its length. It was largely a well-maintained earth road, with some stretches levelled or built up with stone. Archaeologists have found traces of a paved section near Gordion in central Anatolia, and remains of possible way stations in Iran.

The exact route between Anatolia and Mesopotamia remains debated. Some scholars place it through northern Mesopotamia near Arbela (modern Erbil), others further north, and Herodotus’s own figures may combine several routes. What is clear is that the system depended on guarded stations, supplies and a body of officials who kept it running.

Timeline

• c. 547 BC: Cyrus the Great captures Sardis, which becomes the western terminus of the later road. See the fall of Sardis.
• 522-486 BC: Reign of Darius I, who organises the empire’s provinces and road system.
• c. 509-494 BC: The Persepolis Fortification Tablets record travel rations along royal roads.
• 499 BC: Aristagoras of Miletus describes the road to the Spartan king Cleomenes, according to Herodotus.
• c. 430 BC: Herodotus writes his description of the road and its stations.
• 334-330 BC: Alexander the Great’s army advances along roads of the Persian network.

Legacy

Alexander the Great and the Seleucid kings who followed him used the Persian roads, and parts of the network later became sections of the trade routes known as the Silk Roads. The Romans, Parthians and Sasanians all relied on routes first organised by the Achaemenids. State relay posts of a similar kind reappeared in many later empires, from the Roman cursus publicus to the yam system of the Mongols, although historians do not claim a direct line of descent from the Persian model.

The Royal Road also left a lasting image. Herodotus’s praise of the Persian couriers, carved in adapted form on the former General Post Office in New York, is still widely quoted as a postal motto. For the historian himself, see Herodotus and the Histories.

Why it matters

The Royal Road shows how the Persian Empire solved the problem of distance. By combining roads, way stations, rations and relay couriers, the Achaemenid kings created one of the first long-distance communication systems run by a state, a model that later empires would follow.