I am starting a new game - am planning to start on a map of the whole of the ancient world from Britain to the Western part of India. Planning to have the following civs :

Greece
Rome
Persia
Carthage
Arabia
Egypt
Celts
India
Spain (?)/ Portugal (?)
England (?) - dont think so
France/Germany (?)
Mongols/Russia (?)
Byzantium.

Do give me some advice. I am thinking of playing as Persia

destroy them all

what do you mean? do you plan on making a mod of the ancient world or are you going to play as one of those civ's and you're wanting advice on how to win? or are you gonna write a story about your exploits in the game?

persia is nice with the immortals, but civs like greece and carthage have hoplites and NM.which is good for ancient age defense. if you plan on a conquest win, play as persia,the immortals have great attack for such an early unit. yet if you wait for knights i suggest playing as india. War elephants are great. they require NO resources to build and they have an extra hp bar. but only in C3C. Good luck ;)