I’m pretty sure it’s Greece because that’s where they were told to fight. Thermopylae is in Greece. However, if you disagree- Persia would be a good alternate guess because they were from Persia and went to Greece.
Well, Your best answer would be is Greece. Because, The Thermopylae is where the mountain pass was near of the sea in the northern Greece was in site of several battles. Good Luck!
