Claim: The crossing of the unguarded and possibly frozen Rhine River by a mixed group of barbarians in the year 406 initiated a wave of destruction of Roman cities when the crossing transgressed one of the Late Roman Empire's most secure boundaries.
Evidence: The crossing of the Rhine River by a mixed group of barbarians which included Vandals, Alans and Suebi is traditionally considered to have occurred on the last day of the year 406 (December 31, 406). It initiated a wave of destruction of Roman cities and the collapse of Roman civic order in northern Gaul. The crossing transgressed one of the Late Roman Empire's most secure limites or boundaries and so it was a climactic moment in the decline of the Empire. It is not clear why the Irano–Germanic bands crossing the Rhine apparently met no organised military resistance on the Roman side.