Darius I, more commonly known as Darius the Great, reigned as the third King of Kings of the Achaemenid Empire from 522 BCE until his death in 486 BCE. Under his rule, the empire reached its zenith, encompassing vast territories across Western Asia, parts of the Balkans (including Thrace, Macedonia, and Paeonia), the Caucasus, the Black Sea's coastal regions, Central Asia, the Indus Valley in the east, and portions of North and Northeast Africa, such as Egypt (Mudrâya), eastern Libya, and coastal Sudan. His reign marked a critical period of expansion and consolidation for the Persian Empire.

Darius ascended to power through a complex and controversial process. He orchestrated the assassination of Bardiya, the rightful heir to the throne, whom he claimed to be an impostor named Gaumata. Once in power, Darius turned his attention to strengthening and expanding the empire. One of the defining episodes of his reign was his campaign against Greece. This effort aimed to punish Athens and Eretria for their involvement in the Ionian Revolt. Although his forces suffered a significant defeat at the Battle of Marathon, Darius achieved notable victories elsewhere. He successfully reasserted Persian control over Thrace, annexed Macedon, and subjugated the Cyclades and the island of Naxos. His campaign also saw the destruction of Eretria, a Greek city.