well, i don't know much about Palmyran history, but i do know that ES had to sacrifice some things to balance the game. (I know they didnt do it perfectly, and I am
*NOT* trying to start another balancing thread, but the point is they could have done it worse.) For another example, Persia certainly had the wheel, and Greece the Fire Galley, but they don't get those in the game. (I know that the fire galley was due to game mechanics, but it would have helped Greece some.{It needs all the help it can get if I believe half of the posts.} I am also not trying to dis the Persian civ.) However, both of these civs are a lot less playable than Palmyra.
If you look at the tech tree, they get pretty good priests for conversion, ok storage pit techs, the phalanx, the heavy catapult and ballista, the heavy horse archer, the ballista tower, 3/4 of bronze govt techs and 2/4 iron. And they get a very good superunit combo, scythe chariots and armored elephants. If you mix in a few cats/ballitae then this already formidable scene gets downright nightmarish. With their economy (which doesnt really need any techs they dont get) they can finance most of this too, unlike the above civs. (especially Persia.) So you see they can turn their hand to most things.
Last, but in my opinion most important, I don't ever recall anyone using the cataphract against me anyway. I know that the only time that i myself ever used it was when my friend and i were both shang and i was kicking his pasty white rump by mid-bronze. (And even then i only did it to pi$$ him off. ) Of course you could turn this argument on its head and ask since no one ever gets it anyway why not give it to them, but if you read the above statements then you should see why I say this. (Oh why do I even get my hopes up? Oh well, I have already started preparing for the oncoming balancing arguement/flame war.)
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