How close to a realistic Seleukid army would this be?

[Zradha Pahlavan]

Ha ha! Hide behind your walls, Greek! You won't stop the might of the Pahlava otherwise, and even then you're only wasting everyone's time! You should just surrender, then maybe the Great King will be merciful to you...

Other things:
Stone walls won't help much against sapping. The lousy Saka used that trick against me once, and broke through the light infantry that were supposed to hold the line there, resulting in a bizarre battle in which opposing sides of horse archers ran throughout the city shooting at each other, all the while trying to elude each other's lancers.
But if you have a well-armored phalanx group, you can plug any gap in the defense. It's good to have a few of them around, just in case.
Another tactic is to lunge at the nearest steppe town, take it, and hold it long enough to get some regional steppe horsemen. Then you can fight fire with fire.

[Conqueror]

The thread may be old but it's subject is always of interest

Optimizing city defenses VS nomad factions:
* Firstly, build stone walls ASAP. Wooden walls are terrible against nomads that can just shoot arching volleys over them. Stone walls OTOH will basically make any units on ground level arrow-proof, while those on the parapets will at least be protected by the crenellations and increased elevation. Also, any missile units on the walls will have longer range (and maybe more powerful attack?)
* Phalangites tend to not work so well up on walls, so use them on the streets to secure the gate and any holes in the walls. Won't do any good to have more than 3 such units per garrison, so send any extras to serve elsewhere.
* For infantry to defend the walls, you'll want them to have good armour and shields, plus high morale. They'll need to be able to endure clouds of arrows before any assault.
* For missile units on the walls, go for either the best range and attack or the best armour available. Archer-spearmen tend to be better assigned to field armies, although they're not useless on sieges either.
* Don't bother including cavalry in garrisons, beyond one FM governor's bodyguard unit. Your field armies will need all the cavalry you can muster.

Field armies:
* As has been stated already, you need plenty of archers and cavalry. Infantry is primarily used to protect the archers from being charged and run over. Nomadic horse archer units, whether mercenaries or recruited regionals, make extremely useful auxiliaries. Until you can afford such an army, there's little point to seek battle on the field.
* Don't initiate battles if you can avoid it. Provoke and lure the Pahlavans into attacking you. If you go aggressively attacking them, they can lead you on a futile chase till your troops are exhausted and killed.
* Don't build forts at the ends of turns. It may seem like a good idea, but really it's to your disadvantage. Forts are deathtraps: they only last some 4 turns (IIRC) under siege, have only palisades around them (= death by archers) and are a total pain to sally out of. If you get besieged in one it'll be far worse than a regular field battle.

[Titus Marcellus Scato]

Great post! Very useful.

I like to hire mercenaries when playing the Seleucids, it helps a lot. Usually I find it hard to recruit decent factional troops, but I have pots of gold, so hiring mercs isn't a problem.