Emperor Sponsianus (which the BBC shortens to Sponsian) had a reputation for being a fake.
They found coins that had the guy’s face and name on them, sure. But in the old days, they thought the coins were forgeries. They were rough, they didn’t look like Roman coins. And besides, there was no emperor Sponsianus. Or was there?
After the barbarian invasions, Rome was in trouble. Magnus Maximus tried to conquer the Roman empire from Britain. Divisions and intrigues troubled the land. So, who was in charge of Dacia (present-day Romania)?
Unlike Maximus, he does not appear to have been a usurper, but rather a local general who took charge to prevent chaos. General Sponsianus was cut off from the rest of the empire, and so were the people he was responsible for.
Sponsianus had seven coins, some of which have apparently gone missing.
For more information, see the Parisien. Sponsianus, l’empereur romain qu’on croyait inventé de toutes pièces – Le Parisien
or the BBC version. Gold coin proves ‘fake’ Roman emperor was real – BBC News