Herodotus was a Greek historian who lived from approximately 484 to 420 BCE. Much of his life was overshadowed by the Greco-Persian Wars of approximately 499–449 BCE, a series of bitter conflicts pitting the massive Persian Empire against the disunited and fractious Greek city-states. Herodotus examined these conflicts using a unique approach. Earlier Greek historians narrated events from an unscientific perspective, citing the gods as the primary agents of historical development. Herodotus, in contrast, approached the Greco-Persian Wars from a rationalist perspective, attributing the outcome of events to human agency.