Between 499 and 449 BCE, a federation of small Greek city-states — internally divided, frequently at each other's throats, with no common government and no standing army — defeated the largest empire on earth in a series of campaigns that should not have succeeded. At Marathon (490) a heavily outnumbered Athenian hoplite force broke a Persian landing in a single morning. Ten years later the Persians came back under Xerxes with an army of unprecedented size; after the holding action at Thermopylae, an allied fleet trapped and destroyed the Persian navy in the narrows of Salamis (480). The next year, at Plataea, a Greek coalition under Spartan command routed the Persian land army and ended the invasion. Greece — population perhaps two million — survived, intact, the assault of an empire of fifty million.
What the Greeks made of this experience is more important than the wars themselves. Herodotus, who chronicled them a generation later in the first work of prose history we possess, organized his account as a contrast between Greek liberty and Persian despotism: free men fighting for their own city-states and their own laws defeated subjects who fought because the Great King commanded it. This was, of course, partly self-flattering propaganda. The Achaemenid empire was a far more sophisticated, tolerant, and administratively advanced polity than Herodotus admitted — its royal road, its system of satrapies, its standardized coinage, and its protections for conquered peoples (Cyrus had freed the Judaean exiles) outclassed anything in Greece — and Greek 'liberty' meant liberty for free male citizens while slaves did most of the work. But the narrative frame — that something distinctive about Greek political culture had given them a real advantage, that free men fight harder than the coerced — became the founding myth of Western civilization. The military reality was nearer to luck, geography, and the heavy hoplite phalanx fighting in terrain that neutralized Persian cavalry and archers. The victories also funded the Athenian golden age: the silver of Laurion built the fleet, the fleet won at Salamis, and the postwar Delian League — founded to keep fighting Persia — turned into an Athenian empire whose tribute paid for the Parthenon, for the tragedies of Aeschylus, who had himself fought at Marathon, for Pericles and the democracy that financed them. Within fifty years that same imperial confidence would draw Athens into the Peloponnesian War and ruin. Every later Western culture, from Rome to the Enlightenment to the modern American republic, has located part of its self-image in the Persian Wars.
The 'East versus West' frame, with all its distortions, is genealogically traceable to Herodotus. Every contemporary commentator who reaches for the contrast between open democratic societies and centralized autocracies — in coverage of Russia, China, or Iran — is, knowingly or not, working in a tradition that Marathon and Salamis helped establish. The flattering half of the story is durable precisely because it is useful: it lets a society tell itself that its freedoms are also its strengths, and quietly skip the harder question of how often the outcome turned on geography, silver, and luck.