World History

After all we'll probably never know how the coins were deposited where they were found.

Frontier garrisons were rarely over run. The were basically placed there to keep an eye on things and project Rome's power and eventually became trading posts and gateways between Roman and barbarian culture.

Within a few centuries, most of Rome's military had adopted German forms of dress; trousers, large brooches, sword belt and scabbard. German tribes that had developed friendly relations with the Romans were tapped for troops when needed (foederati). By the 4th and 5th centuries Germans often headed large contingents of Roman troops (magister militum or patricius). Not that the cultural exchanges were one way, but the 5th century most German nobles were nominally christians, though they practiced a non-Catholic version which would create further divisions.

I'd liken this situation to our southern border with Mexico. Over time the US has developed an appreciation for meso-American cultural items (food for instance) and those south of the border seemed to have developed western consumption practices.