Darius I (Old Persian: Darayavahu�) (550 � 486 BCE), also known as Darius the Great, was the fourth king of kings of the Achaemenid Empire. Darius held the empire at its peak, then including Egypt (Mudr�ya) , Balochistan, Kurdistan and parts of Greece. The decay and eventual downfall of the empire commenced with his death and the ascension of his son, Xerxes I.

Darius ascended the throne by overthrowing the alleged magus usurper of Bardiya with the assistance of six other Persian noble families; Darius was crowned the following morning. The new emperor met with rebellions throughout his kingdom and quelled them each time. A major event in Darius's life was his expedition to punish Athens and Eretria for their aid in the Ionian Revolt and subjugate Greece. Darius expanded 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.