Darius successfully invades southern Russia in a campaign against the Scythians east of the Caspian Sea.

Darius invades the Balkans in 515 BCE but fails in his attack on the lower Danube tribes.

The Middle East: 525–514 BCE

Ascendancy of Darius and Imperial Reorganization

The era 525–514 BCE marks a turbulent yet transformative period within the Achaemenid Persian Empire. In 522 BCE, Cambyses II, Persia’s second Achaemenid king, dies under ambiguous circumstances—either by suicide or accident—in Syria, during his return from Egypt to suppress a revolt. The rebellion is led by a figure claiming to be Cambyses’ younger brother Bardiya (known as Smerdis to the Greeks). Bardiya's rule, beginning in March of the same year, proves ephemeral, lasting no more than eight months. In September, Darius, a noble and member of Cambyses' royal bodyguard, along with other Persian aristocrats suspicious of Bardiya’s legitimacy, assassinates him.

Darius, the son of Hystaspes, satrap of Parthia, subsequently ascends the throne. He justifies his claim by declaring the slain Bardiya an impostor named Gaumata the Magian, alleging that the true Bardiya had been secretly murdered by Cambyses years prior. Despite these assertions recorded in Darius’ trilingual inscription at Behistun, many modern scholars question their authenticity, suggesting Darius fabricated the account to legitimize his usurpation.

Under Darius, the Persian Empire becomes notably centralized, stretching from the Mediterranean to the Indus Valley, facilitated largely by Cambyses’ earlier conquest of Egypt. A skilled administrator, Darius reorganizes the empire into administrative regions known as satrapies, each governed by a satrap responsible for maintaining order and forwarding taxes. He establishes an efficient central bureaucracy, implements a standardized legal system called the Universal Law (the King’s Law), and organizes an extensive postal system operating along the empire’s Royal Roads. Furthermore, Darius introduces a standardized currency, minting gold coins known as darics, to facilitate trade and economic stability across his vast territories.

Culturally, Darius is a significant patron, promoting Zoroastrianism throughout his domains. He reportedly commissions the creation of a new cuneiform script for Old Persian to facilitate communication and administration. His monumental trilingual inscription at Behistun, carved onto a sheer cliff face along the ancient highway linking Babylon and Ecbatana (modern Hamadan), commemorates his decisive victory in 521 BCE over Gaumata and various rebellious satrapies. Above this inscription, a striking bas-relief depicts Darius with a bow and spear, his foot triumphantly placed upon the prostrate Gaumata, while the winged god Ahura Mazda symbolically acknowledges his authority.

In 518 BCE, Darius initiates ambitious construction projects, notably at Persepolis—a royal complex near modern Shiraz in southwestern Iran, located about fifty miles (eighty kilometers) south of Pasargadae. Built atop an imposing limestone platform for stability and prominence, Persepolis becomes a grand architectural testament to Achaemenid power and artistry.

Early in his reign, Darius faces significant resistance and must subdue numerous spontaneous revolts across regions such as Susiana, Babylonia, Media, Sagartia, and Margiana, where local authorities have attempted to assert independence. Additional military actions occur in Armenia and Parthia, further demonstrating his resolve. By successfully quelling these widespread insurrections—including a decisive third revolt in Susiana—Darius solidifies his imperial authority, ultimately crushing nine rebellious leaders through nineteen separate battles. His victories enable further expansion and consolidation, fortifying the Persian Empire as the dominant power in the Near East during this critical era.

Cambyses II, Persia’s second Achaemenid king, either commits suicide or dies accidentally in Syria in the summer of 522 BCE while returning to Persia from Egypt, supposedly to deal with a revolt by a usurper claiming to be Cambyses’ younger brother Bardiya, called Smerdis by the Greeks. (The Greek historian Herodotus, writing a century later, will allege in his history that Cambyses was insane.)

Having supposedly taken the throne in March, Bardiya reigns for no more than eight months before being slain in September by Darius—a member of the late Cambyses’ royal bodyguard—and other Persian nobles suspicious of his origin.

Darius, the son of Hystaspes, the satrap of Parthia, ascends the Achaemenid throne, claiming that he is restoring the kingship to the rightful Achaemenid royal family, of which his is a collateral branch. (As Darius’ father and grandfather are alive at his accession, it is unlikely that he is next in line to the throne. According to Darius' account in his later trilingual inscription at Bisitun, Cambyses had secretly murdered Bardiya years before, and the usurping Bardiya was a successful impersonation by Gaumata the Magian. Certain modern scholars consider that Darius fabricated the story of Gaumata to justify his actions and that his murdered predecessor had indeed been a son of Cyrus.)

Cambyses’s conquest of Egypt has allowed the relatively benevolent Darius to rule a centralized empire from the Mediterranean to the Indus.

He divides the Achaemenid empire into satrapies for administrative convenience, organizes the postal system on the royal roads, institutes an efficient central bureaucracy, and strives to standardize legal practices throughout the empire with the imposition of Universal Law (the King’s Law).

He mints gold coins called “darics.”

Zoroastrianism spreads with Darius’s encouragement.

Darius reportedly orders the creation of a cuneiform script for the (Old) Persian language.

He records his early struggles in a trilingual inscription (in Old Persian, Babylonian, and Elamite) on a precipitous cliff face at Behistun (beside the ancient highway between Babylon and Ecbatana—modern Hamadan—near Kermanshah in western Iran), near to where he gained a decisive victory in 521.

The text includes an autobiographical account of events leading up to the battle, along with a list of satrapies of the empire.

A bas-relief of Darius, attended by bow and spear warriors, stands above the inscription, his foot placed on the prostrate and supplicating figure of his defeated enemy Gaumata; nine other captive rebel leaders stand behind him.

Above the victor scene hovers the winged god Ahura Mazda, acknowledging the king's salute.

A great patron of the arts, Darius initiates construction on a complex of palaces and buildings at the royal complex of Persepolis (near modern Shiraz in southwestern Iran) around 518 BCE.

Located about fifty miles (eighty kilometers) south of Pasargadae, Persepolis, as was also typical of Assyrian palace complexes, is constructed atop a huge limestone platform that serves to level off the site and provide a secure foundation for its structures.

Darius, not generally recognized as Persia’s king, thus imposes his rule by force, fighting many spontaneous rebellions against his authority early in his reign, in such places as Susiana, …

…Babylonia, …

…Media, Sagartia, and Margiana, where independent governments had been erected.

Circumstances force him to also send troops to …

…Armenia and …