Only babylon has mounted archers?

[HannibalExMachina]

As the topic says, i found it always strange that in ROP babylonia has mounted archers (a fact i found very interesting), but none of the the more "cavalery based" armies (like persia, bactrains etc.) have them. Are they a feature which will be added later, or is it just a fact that at this time (6th century), they were completly uncommon at "steppe" or "steppe descended" peoples?

[rez]

Well whilst the Persians preferred using Palta (javelins) in battle, they used bows on horseback during hunting. The Medes and other Iranian people like the Bactrians used horse archers and as soon as those factions are finished you'l be able to see some more horse archers.

As for the Babylonians there is a huge wealth of rock reliefs that depict assyrian and Babylonian armies fighting with horse archers.