The Sassanids took over from the Parthians around the 3rd century ad until they were defeated and conquered during the Arab Conquest in the 7th Century.
While principally a mounted army they did use ally and client troops and militias to form the infantry component.
These are test shots from Hat set 8267 Sassanid Light Infantry.
Slingers
Archers - these can be independent units or stuck on the back of Levy units.
Javelin Skirmishers
