Darius I (550 – 486 BCE), also known as Darius the Great, is the third king of the Achaemenid Empire.

Darius holds the empire at its peak, at this time including Egypt (Mudrâya), Balochistan, Kurdistan and parts of Greece.

Darius ascends the throne by overthrowing the alleged magus usurper Bardiya with the assistance of six other Persian noble families; Darius is crowned the following morning.

The new emperor meets with rebellions throughout his kingdom and quells them each time.

A major event in Darius's life is his expedition to punish Athens and Eretria for their aid in the Ionian Revolt and subjugate Greece.

Darius expands his empire by conquering Thrace and Macedon and invading Scythia, home of the Scythians, Iranian tribes who had invaded Media and had previously killed Cyrus the Great.

Darius organizes the empire by dividing it into provinces and placing satraps to govern it.

He organizes a new uniform monetary system, along with making Aramaic the official language of the empire.

Darius also works on construction projects throughout the empire, focusing on Susa, Pasargadae, Persepolis, Babylon and Egypt.

Darius devises a codification of laws for Egypt.

He also has the cliff-face Behistun Inscription carved, an autobiography of great modern linguistic significance.

Darius also starts many massive architectural projects, including magnificent palaces in Persepolis and Susa.