In a Baktrian campaign I would suggest Paya Hinam Dunai Purma (Subeshi Archers) which are easily recruitable in the provinces to the north and east of the Baktrian capital. The have more ammo, longer range higher defense and a better secondary than the Persian and Caucasian Archers. They are about 50 mnai more upkeep but well worth it.

Attack: 5
Range: 198
Ammo: 35
Secondary: .1 sword
Defense: 12