The Rhine and Danube rivers had become the effective borders between Roman governed territory of Germania and the multiplicity of Teutonic tribes that were dispersed across northern Europe. Over the two centuries that followed the shocking attack by the Cherusci tribe on the Roman army in the Teutoberg Forest (9 CE), which resulted in the death of over 20,000 legionaries, fighting between German tribes and incursions into the Roman Empire was relentless. As the Germanic tribes migrated westwards they displaced rival tribes in their wake, often driving them towards the Roman frontier. The Romans responded by building substantial fortifications, called limes, along the river borders, which reached their greatest extent in the 2nd century. On land the frontiers comprised ditches, palisades, and – in places – stone walls, punctuated by watchtowers and approximately 120 forts. Four permanent legions were garrisoned in Germania Inferior and Germania Superior, supplemented by auxiliaries. While policing the frontier was a full-time commitment there were also a number of focused campaigns against the tribes, notably Marcus Aurelius’s assault on the Marcomanni and Quadi tribes from 166–180 CE. The heavily fortified frontier was not impenetrable; it was a porous border between Rome and the ‘barbarian’ lands, and was frequently crossed by traders. While the Romans exported fine metalwork, pottery and glass across the Rhine, they imported raw materials such as amber, leather and slaves.
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