- PERSIAN COMPANIONS (IMMORTALS):
these guys are the new ceremonial guard of the rising Persian Empire, mimicking the old (well, 50 years old) achaemenid Immortals. Apparently the Sassanids also had a honour guard like this centuries later, and it would be only sensible for our new Persians to restore them when they have disappeared so shortly before. They still fight with bow, spear and shield, which in game translates into a blurry unit which has got good armour, good firepower, good melee capabilities, but specializes in none. Dedicated melee elite units will still hack them down and they won't stop cataphracts, just like I want them. Because I'd also like to remind that 10 thousands of them broke under the charge of the Alexander's Companions (which is also why they don't have the traditional morale 70 of the elite units).
With the current balance they are the ultimate archers and (SPOILER) an excellent counter to horse archers and flanking unit.
Recruitable in Noble III-IV (xp 2), Persia only.
Note: disable FireAtWill during melee combat for better performance (as with all missile units).

- PERSIAN IMMORTAL CATAPHRACTS:
the royal guard that gets the real stuff done. The Sassanids had them, most often in reserve or to deliver the final punch. They are the ultimate cataphract units in the game, period. Is there a catch or are they OP? (shame on you, Cataph!) nope, there's a catch. You only get them as general units with second tier final researches; additionally, when you get to recruit them Heavy Stables IV (1 xp) they are capped to 10. For Persia, Media and Atropatene only, as they are the heart of any Persian Empire.

- PERSIAN CATAPHRACTS:
a step ahead of basic eastern cataphracts, your cataphract generals will reform to them when you research the Heavy Stables III. For Persia, Media and Atropatene only, again.

- PERSIAN LIGHT HORSE:
basic riders with some degree of protection, an axe and precursor javelins, to cover the same role as the hellenic Light Cavalry and to fill the spot of the tribal light cavalry.
Recruitable in LevyIII+ and Light Stables II+, with growing experience bonus.

- PERSIAN SPARABARA:
It was the most reliable component of the expendable horde of spearmen Persia could field, with some degree of training and armouring. In game, they provide a decent infantry line with good protection and a helpful shield screen. The fact that they will get in your garrisons comes as a huge bonus to the heavy infantry-starved persians.
They fully replace Eastern Spearmen with Military Method research.

- PERSIAN TAKABARA:
Better equipped axemen, which in game can be surprisingly choppy but are still too untrained and lightly armoured to be an actual melee line.
They fully replace Hillmen with Military Method research.

- PERSIAN INFANTRY:
Like many armies to come in the future, the Persians often armed their conscripts with baseline defensive equipment and bows, because you can't get into melee with a poor spearmen if you are being showered by thousands of arrows. Gamewise, they will be torn apart by whatever non-conscript unit who has got a shield or armour heavy enough to repel basic arrows. Nonetheless, they will probably win a lot of skirmishing contests.
They fully replace Eastern Garrisons with Weapon Proficiency research.

- PERSOHELLENIC PIKES:
a compromise between Levy and regular Pikemen, with the bonus of being resistant to heat due to hybridization and having beards.
Recruitable in NobleII+ and LevyIII+.

- OSROENE HILLMEN:
tough skirmishers from the perso-arabian kingdom of Edessa. It was apparently customary for recruiters that happened to pass by to get some of these guys. Here represented as melee-capable peltasts, comparable to the Thracians.
Recruitable in LevyII+, Atropatene only.

- OSROENE PELTASTS:
we are here assuming that the power ruling over the region would absorb this capable native force into its own regular army. The result would have been aggressive heavy peltasts.
Recruitable in Levy IV, Atropatene only.

- BABYLONIAN GUARD:
A 'fantasy' unit, median nobles fighting as a honour guard in the hoplite style, due to their closer vicinity to the hellenic influence, as an ideal garrison of the faboulous Ishtar Gates. They're comparable to the armenian Nobles rather that to an hellenic hoplite elite unit.
Recruitable and unlocked as general with the NobleIII barracks, Media only.

- ARACHOSIAN SILVER SHIELDS:
The original Argyraspides were spread around the hellenic empires, often in squads of two men, to be slowly killed off during their tasks because they were just too dangerous to be kept around. Many seemingly ended up in the far Arachosia. We are here assuming that the local nobles and a few hellenes are keeping their memory alive fighting as hoplites. Comparable to the Bactrian Royal Guard rather than to macedonian Hypaspists.
Recruitable with the Noble IV barracks, but a starting general unit; Arachosia only.

- INDIAN LONGBOWMEN and LEVY SPEARS:
Indian conscripts were pretty common around the Indus valley. They were not valuable infantry per se without their numbers, and even then they were pretty unreliable in holding the line, as the Bactrians well knew. Their archers could although be surprisingly effective with their large bows, often made out of cane or bamboo and firing poisoned arrows. Gamewise, they are represented as stealthy but cheap and expendable units (because you can't have enough crappy levies).
Recruitable in LevyII+ barracks, for Arachosia, Drangiana and Bactria.


That's all for now, folks!