peoples. Apparently, this distinction was first made by Julius Caesar, whose main concern was to argue that raids into southern Gaul and Italy by northern peoples who were less softened by Mediterranean civilization, should be seen in Rome as a systematic problem that can repeat in the future, and thereby demanded pre-emptive military action. This was his justification for invading northern Gaul.

After Caesar, Strabo (died circa AD 24) and Marcus Velleius Paterculus