He ruled the empire at its territorial peak, when it included much of West Asia, parts of the Balkans (Thrace–Macedonia and Paeonia) and the Caucasus, most of the Black Sea's coastal regions, Central Asia, the Indus Valley in the far east, and portions of North Africa and Northeast Africa including Egypt (Mudrâya), eastern Libya, and coastal Sudan.

[1][2] Darius ascended the throne by overthrowing the Achaemenid monarch Bardiya (or Smerdis), who he claimed was in fact an imposter named Gaumata.

The new king met with rebellions throughout the empire but quelled each of them; a major event in Darius's life was his expedition to subjugate Greece and punish Athens and Eretria for their participation in the Ionian Revolt.

Although his campaign ultimately resulted in failure at the Battle of Marathon, he succeeded in the re-subjugation of Thrace and expanded the Achaemenid Empire through his conquests of Macedonia, the Cyclades, and the island of Naxos.

He organized Achaemenid coinage as a new uniform monetary system, and he made Aramaic a co-official language of the empire alongside Persian.

[4] At some time between his coronation and his death, Darius left a tri-lingual monumental relief on Mount Behistun, which was written in Elamite, Old Persian and Babylonian.

May Ahuramazda protect me and my royal house!Herodotus, a Greek historian and author of The Histories, provided an account of many Persian kings and the Greco-Persian Wars.

[7] However, according to Lloyd Llewellyn-Jones (2013), recently uncovered texts in Persepolis indicate that his mother was Irdabama, an affluent landowner descended from a family of local Elamite rulers.

[20] However, once Cyrus had crossed the Aras River, he had a vision in which Darius had wings atop his shoulders and stood upon the confines of Europe and Asia (the known world).

When Cyrus awoke from the dream, he inferred it as a great danger to the future security of the empire, as it meant that Darius would one day rule the whole world.

The oldest records report a convoluted sequence of events in which Cambyses II lost his mind, murdered his brother Bardiya, and was killed by an infected leg wound.

After this, Darius and a group of six nobles traveled to Sikayauvati to kill an usurper, Gaumata, who had taken the throne by pretending to be Bardiya during the true king's absence.

Darius's account, written at the Behistun Inscription, states that Cambyses II killed his own brother Bardiya, but that this murder was not known among the Iranian people.

Darius, who had served Cambyses as his lance-bearer until the deposed ruler's death, prayed for aid and, in September 522 BCE, along with Otanes, Intaphrenes, Gobryas, Hydarnes, Megabyzus and Aspathines, killed Gaumata in the fortress of Sikayauvati.

After stating that a republic would lead to corruption and internal fighting, while a monarchy would be led with a single-mindedness not possible in other governments, Darius was able to convince the other nobles.

[7] The details regarding Darius's rise to power is generally acknowledged as forgery and was in reality used as a concealment of his overthrow and murder of Cyrus's rightful successor, Bardiya.

Darius began to fear for his own safety; he thought that all seven noblemen had banded together to rebel against him and that the attack against his officers was the first sign of revolt.

[35] Taking precautions against further resistance, Darius sent soldiers to seize Intaphernes, along with his son, family members, relatives and any friends who were capable of arming themselves.

[40] Through another series of campaigns, Darius I would eventually reign over the territorial apex of the empire, when it stretched from parts of the Balkans (Thrace-Macedonia, Bulgaria-Paeonia) in the west, to the Indus Valley in the east.

In 516 BCE, Darius embarked on a campaign to Central Asia, Aria and Bactria and then marched into Afghanistan to Taxila in modern-day Pakistan.

For a year and a half, Darius and his armies were unable to retake the city, though he attempted many tricks and strategies—even copying that which Cyrus the Great had employed when he captured Babylon.

[43] The Scythians were a group of north Iranian nomadic tribes, speaking an Eastern Iranian language (Scythian languages) who had invaded Media, killed Cyrus in battle, revolted against Darius and threatened to disrupt trade between Central Asia and the shores of the Black Sea as they lived between the Danube River, River Don and the Black Sea.

[48] Darius eventually ordered a halt at the banks of Oarus, where he built "eight great forts, some eight miles [13 km] distant from each other", no doubt as a frontier defence.

Darius also conquered many cities of the northern Aegean, Paeonia, while Macedonia submitted voluntarily, after the demand of earth and water, becoming a vassal kingdom.

After becoming aware of the Persian defeat at the Battle of Marathon, Darius began planning another expedition against the Greek city-states; this time, he, not Datis, would command the imperial armies.

[7] Soon afterwards, Darius died, after thirty days of suffering through an unidentified illness, partially due to his part in crushing the revolt, at about sixty-four years old.

[7] To ensure that one person did not gain too much power, each satrap had a secretary, who observed the affairs of the state and communicated with Darius; a treasurer, who safeguarded provincial revenues; and a garrison commander, who was responsible for the troops.

[7] The imperial administration was coordinated by the chancery with headquarters at Persepolis, Susa, and Babylon with Bactria, Ecbatana, Sardis, Dascylium and Memphis having branches.

[7] However, Darius gathered a group of scholars to create a separate language system only used for Persis and the Persians, which was called Aryan script and was only used for official inscriptions.

[7] Early on, Darius and his advisors had the idea to establish new royal mansions at Susa and Persepolis because he was eager to demonstrate his newfound power and leave a lasting legacy.