Here is a nice Constantius II falling horseman I recently acquired:
AE Centenionalis
Constantius II, 337-361 CE
Diameter: 21 mm, Weight: 6.32 grams, Die Axis: 6h
Obverse: D N CONSTANTIVS PF AVG
Diademed, draped and cuirassed bust to right.
Reverse: FEL TEMP REPARATIO
Soldier (described also as Constantius II or the personification of Virtus) to right holding shield, spearing falling enemy horseman to left. Horseman tumbles over neck of horse, facing forwards with arms outstretched.
Mint: ANΘ, Γ in field to left: Antioch
The reverse retains some nice details. The 'barbarian' is sometimes described as a Goth or Parthian on these types. I'm not sure why, since the Parthian empire had fallen by the time of Constantius II. Of course this type could be a reference to an earlier event in Rome's history, but it seems more likely to be celebrating Constantius II's own battles with the Sassanid Empire then ruled by Shapur II.
The two statues below were found in Hatra, Iraq and are dated to the 3rd century CE. The first with the peaked cap is thought to be Sanatruq II, king of Hatra circa 205 to 240 CE. The second is a statue of a 'noble'. Hatra was an important border city with a cosmopolitan population, that at times included Romans. It was captured and sacked by Shapur I circa 241CE. The dress on both statues, particularly the trousers, is remarkably similar to the fallen horseman on Constantius' coin. It suggests the engraver was familiar his subject, and that the falling horseman is more than just a generic 'foreigner'.