[Cronos]

Indeed, except for the Scythians [who the Persians had been fighting since the time of Cyrus the Great [they killed him]in the southern Steppe, there weren’t a lot of people around up that way [the great migrations started later] for the Persians to fight. And not much [wealth, ports, etc] to fight over.

I disagree with that -- the Persians had to initially fight off the Babylonians and the Medes and prior to that the all-powerful neo-Assyrian Empire had been defeated.

Beside the Scyths, the Persians had to contend with powerful Indian dynasties and the Egyptians

and wealth -- there was a lot of it in the fertile crescent, indus valley and Canaan.

[PzLdr]

You’re right. But the thrust of the article, as I understand it, posits a Persian thrust to the northwest of Greece, at a time when the Babylonians, Assyrians and Medes had already been assimilated into the Persian Empire. So I wrote accordingly.

One other factor the Persians would have faced with the Romans was spectacularly deep manpower pool that was largely homogeneous and higly militarized using the same system [see Second Punic War].