The Greeks were prolific breeders, which is why they established colonies all around the Mediterranean and Black Seas to provide for their excess population which could not be maintained in such a poor countryside as mainalnd Greece.
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The Persian War lasted spasmodically for fifty years, and the casualties in the war were no more able to absorb the excess population than had the normal internal wars before and after the Persian War.
So the colonies continued to be established, then and later.