This bronze coin is a contemporary counterfeit of a follis of the Roman emperor Constantius II (337-361). In 353 AD, Constantius closed several mints in the German and Gallic parts of the Empire, which resulted in a shortage of money. The lack of currency led to an increase of coin forging – people had already gotten so used to money that its absence caused problems in every day life.
The 'imitations,' forgeries actually, are easy to recognize by their rough style. This piece was produced in the vicinity of Lyon, or at least it is modeled after an imperial follies from the mint of Lyon.