A mythical beast with the body of a lion, head of a man, and the sting of a scorpion.
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After the Persian victories at Artemisium and Thermopylae, king Xerxes proceeded to Athens, which he captured in the last days of September 480. Meanwhile, the Greek navy, which had managed to get away from Artemisium, stayed on the isle of Salamis, opposite Athens. The presence of the enemy close to Phaleron, the Athenian harbor, created a strategic problem for the Persians: they could not use their port as easy as they wanted. And this was something they had to, because their army was proceeding to the Isthmus of Corinth, and it was imperative that the transport ships, brimful with food, could join the soldiers on the Isthmus. It was, therefore, imperative to expel the Greeks from Salamis.
Answer:
That's where they were able to find the resources they needed for economic growth like minerals such as iron and gold. They didn't settle somewhere else because no other land had the resources they were looking for.