The Great Wall of China
Beyond the borders of the empire lived many peoples that the Romans called barbarians, that is, foreigners. Some, such as the Gauls and the Britons, had already been conquered for some time and had become part of the empire. Others did not know the laws of Rome, they did justice for themselves in long chains of crimes called feuds. Many were nomads.
The Western Roman Empire, increasingly weak and poor, allowed the more civilized barbarian populations to settle within their own borders. In exchange for lands, foreigners became soldiers of Rome.