The barbarian invasions destroyed Western Europe. The Roman Empire ruled Western Europe. The decline of the Roman Empire was when it failed to control and rule over its territories. The Roman Empire broke up into smaller territories. The barbarians were then able to invade Western Europe. The rise of Christianity and continual pressure from the barbarians on the Roman Empire's borders were some of the factors that contributed to the break-up of Western Europe. The rule of the Roman Empire was over when Rome fell to the conquering invaders