So between 490 and 480 BCE, the Persians made war on the Greek city-states. This was the war that featured the Battle of Thermopylae, where 300 brave Spartans battled, if you believe Herodotus, 5 million Persians. And also the Battle of Marathon, which is a plain about 26.2 miles away from Athens. The whole war started because Athens supported those aforementioned Ionian Greeks when they were rebelling in Anatolia against the Persians. That made the Persian king Xerxes mad, so he led two major campaigns against the Athenians, and the Athenians enlisted the help of all the other Greek city-states. In the wake of that shared Greek victory, the Greeks began to see themselves as Greeks rather than as Spartans or Athenians or whatever. And then Athens emerged as the de facto capital of Greece and then got to experience a Golden Age, which is something that historians make up.