How Highways Helped the Ancient Persians Become the World’s First Superpower

Everyone, it seems, is familiar with highways constructed by the ancient Romans. Those elegant, stone-paved roads pop up as supporting actors in every novel, film, or television show set in Roman times. Yet few people seem aware that this vast Roman transportation network was preceded by another system of imperial highways that was much older yet just as incredible—the Royal Road of Achaemenid Persia (ancient Iran). 

It is no exaggeration to call the Achaemenid Empire (550 BCE–330 BCE) the world’s first superpower. Persia conquered lands and conducted military operations on three continents: Asia, Africa, and Europe. Not even the mighty Assyrian Empire in Mesopotamia which preceded it could make such a claim.

The Persians were at first considered minor players in the region. Nobody suspected that Persia would rise to greatness as it accompanied Median allies to bring down the Assyrian Empire. Yet in 550 BCE, Persian king Cyrus II—later dubbed “Cyrus the Great”—overturned his Median masters and established the first Persian Empire.  The Persians became rulers of the civilized and densely populated Mesopotamian core. Over the next 64 years, Achaemenid Persia would push the boundaries of its expanding empire west into the Balkans, as far as modern Bulgaria, south as far as Libya in North Africa, and east into the jungles of the Indian subcontinent.

The Need For Speed

Persia inherited the problems of ruling a vast empire. Difficulties resulted from the vast distances between the Persian capitals and outlying satrapies. This problem proved a tough nut for the Persians to crack. Ironically, the Persians’ rapid rate of expansion throughout its early years would only exacerbate the issue.

Persia’s third ruler, Darius I (522–486 BCE) realized the potential benefit to be gained by connecting the empire’s various and distant parts. Along the way to earning the moniker “Darius the Great,” he initiated a program of road construction, maintenance, and administration that would last well beyond not only his lifespan, but that of his empire’s as well.

The terrain encompassed by the Persian Empire varied widely from the foothills of the Zagros Mountains in Iran to the plains, deserts, and even swampy marshes of Central Mesopotamia. It included the lofty peaks of the Hindu Kush and the vast deserts of Egypt. Innumerable rivers required bridging or permanent ferries to cross. Much physical labor was required to make steep slopes and soggy marshes traversable.

Under Darius I, engineers connected the principal cities at the heart of his empire, including the royal palaces at Susa, Babylon, Ecbatana, Pasargadae, and Persepolis. The Persian court rotated annually between these locations, which also led to an interconnected network of garrisons and storehouses required to facilitate the security and transport of the mobile royal court.

The intricate highway-based infrastructure expanded. Ancient Greek historian Herodotus described rest stations and inns located every 30 kilometers, essentially a day’s travel. These facilities provided fresh horses for royal messengers, food for travelling officials and merchants, and secure resting places for sanctioned trade caravans. The Persians regulated access to and use of the Royal Road through a system of licensing and taxation with the issuance of viyataka, a type of official pass. 

First Mobile News Network?

Many royal posting stations were adapted to pass simple messages through the use of signal beacons, relaying from one station to the next and covering vast distances in an incredibly short period of time. These simple messages provided warning to the Great King of an impending situation or developing problem, to be followed up by a more detailed message carried by swift horse and imperial rider. 

The Persian road system allowed news to be delivered from anywhere in the empire to the royal court within a day or two of its occurrence—a remarkable achievement in ancient times. This provided the Persians a significant military advantage in terms of being able to speedily react to intelligence. Imperial stations along the Royal Road ensured the king’s commands were delivered in the shortest possible time. 

Today, the total length of the Royal Road network is estimated at 8,000 miles. This includes the identification of Persian highways stretching from Kyrgyzstan and India in the east, to Türkiye and Egypt in the west. The network crisscrossed the vital Mesopotamian heartland, connecting cities, regions, and cultures.

Very few Persian highways were paved. Yet even Persia’s unpaved highways, with a standard width of roughly six meters, were considered flat and durable enough for traffic by wheeled vehicles that otherwise struggled to cross predominantly sandy or rocky terrain. These highways were more than sufficient to handle chariot, wagon, cavalry, and foot traffic. 

Armies on the Go

Persian roads greatly facilitated the movement of large armies. Alexander the Great made extensive use of the Persian road network even while he was tearing that ancient empire to shreds. A failed 330 BCE attempt by a Persian general to stop Alexander’s army from proceeding down the Royal Road through a natural chokepoint became known as the Battle of the Persian Gates. The value of the Persian highways appears to have been abundantly clear to Alexander. He took advantage of the interior lines they provided him throughout his eastern campaigns.

Persian roadways evinced mythological origin stories from Greeks who encountered them. One attributed the construction of the Royal Road to the Syrian warrior goddess Smiramis, who the Greeks believed to have founded ancient Babylon. Another Greek legend gave the credit to Memnon, a mythical king of Ethiopia and conqueror of all the territory between Susa and Troy.

When the Romans arrived on scene in the 2nd century BCE, the decaying Persian road network no doubt contributed to the speed with which Pompey the Great subdued the entire Eastern Mediterranean. Many, if not most, of the Roman roads eventually constructed across Asia Minor, Judah, and Mesopotamia were laid atop the old Persian thoroughfares. A portion of one such stretch has been positively identified near Gordium in modern Türkiye, displaying multiple strata of road construction stacked atop one another. 

Still in use Today

Considering the massive scope of the Achaemenid Persian road system, one might be surprised to find so little evidence of it today. In 2019, archaeologists discovered the long-buried ruins of a Persian postal station in the village of Toklucak, Türkiye.  Ongoing excavations along the Syr Darya River in Kazakhstan and Kyrgyzstan offer enticing insights into the Royal Road that once connected Mesopotamia with the ancient lands of Bactria and Ferghana. Bridge footings, deliberate cuts into steep slopes, and foundations of once bustling inns and postal stations are slowly emerging.

The principal reason why so few remnants of Persia’s road system have been found is the fact that people still essentially use it—the modern road system to a large degree still utilizes the routes first surveyed and graded by Achaemenid Persians some 2,500 years ago.

Royal Roads passing through historically restrictive terrain as the Cilician Gates are now asphalted motorways through which thousands of vehicles and even more people traverse each day. Those commuters remain blissfully unaware that the foundation for their comfortable journey was first laid down in the 6th century BCE.

this article first appeared in military history quarterly