In what year does Assassin's Creed Odyssey mainly begin?

Assassin's Creed Odyssey mainly begins in 431 BCE, at the start of the Peloponnesian War.

The game is set in ancient Greece and follows a Spartan mercenary during the conflict between Athens and Sparta. Players choose either Kassandra or Alexios as the playable character, while the game's broader story explores the player's family, the Cult of Kosmos, and ancient technology.

The date 431 BCE marks the traditional beginning of the Peloponnesian War, when hostilities between Athens and Sparta escalated into a long-running conflict. Odyssey uses that historical framework while combining real locations and figures with fictional characters and myth-inspired elements.

Odyssey should not be confused with Origins, which is set in Ptolemaic Egypt several centuries later, or Valhalla, which takes place mainly in the Viking Age. The game also predates the formal Hidden Ones organization shown in Origins.