Rise of Persia will add - to the regular game and the other DLCs as well – units like the Praetorian Guard, Praetorian Guard (Late), Greek Peltasts, Thracian Peltasts, Massed Thracian Peltasts, Thracian Spearmen, and several other new units for free! These new units are part of a major army list overhaul affecting Greek, Thracian, 1st-3rd century AD Roman, Sassanid, Parthian, Indo-Parthian, Kushan and Byzantine army lists.
Kudos to the developer for this great work!
Look at the screenshots below!
Get more information about Rise of Persia from its official product page
Massed Thracian Peltasts