Beyond just being historically accurate, Persia is a great choice for Xerxes as you can earn two unique military units, the Immortal and the Hazarapatis. Plus, Infantry Units gain +3 Combat ...

Persian King Xerxes led a Army of well over 100,000 (Persian king Xerxes before war has about 170,000 army) men to Greece and was confronted by 300 Spartans, 700 Thespians, and 400 Thebans.

Xerxes had spent years planning his invasion ... On the coast a fleet of some 1,200 ships amassed, while on land over 100,000 (or 1.7 million according to Herodotus' exaggerated account) soldiers ...

Persian King Xerxes led a Army of well over 100,000 (Persian king Xerxes before war has about 170,000 army) men to Greece and was confronted by 300 Spartans, 700 Thespians, and 400 Thebans.