They were a fragmented group of city-states. You have the famous Athens, Corinth, Sparta, all of these city-states. They shared a common language. They shared similar religion, but they were not one unified empire. But when their brethren, the Greek rebels, these Ionic rebels, I guess you could say, rose up against their Persian rulers, they had assistance from Athenians and from folks in Eritrea. And so when Darius finds out about this, not only does he want to take back what the rebels had, he wants to suppress them, he wants to put down that rebellion, he also wants to have revenge on the Athenians and the Eritreans. And so the first thing he does is he sends out a fleet in 492 BCE.