While the plague of Justinian did strike scattered cities in northern Europe, it did not ravage the whole Continent for two reasons. First, in Europe the disease was conveyed primarily over Mediterranean routes, and the way west and north was blocked by the Goths, Vandals, and Huns. Second, by the sixth and seventh centuries, the essential intermediate host, the black rat, had not yet expanded much beyond the Mediterranean littoral, and certainly not yet to the continent’s Atlantic ports.
