The Romans fought against the ‘barbarians’ for the entire lifespan of their Empire. Caesar’s Gallic Wars detailed endless campaigns against European and English tribes. By the 5th C. AD/CE Rome was exhausted and barbarian depredations menaced the Eternal City itself. Terry Jones a British popular historian has a multiple series on the full history of barbarians. He uses humour and good visuals to present a sprawling history. If you have a few hours you can binge on barbarians throughout the Middle Ages. Start here
