In the late fifth century BC, the Celts began to move southwards, across the Alps, and eastwards, into the Balkans. Regardless of the motivations for their travels – Livy, for example, gives overpopulation as the reason (5.34.2) – these were migrations, not invasions. Of course, these Celtic groups were migrating into lands that were already occupied, which would lead to conflict with the local population.
In Italy, in the early fourth century BC, the Celts there first clashed with the Etruscans, “envying the beauty of their lands” (Polybius, 2.17), and then, expanding south, attacked Rome, sacking the city (Livy, 5.41–43). In the Balkans, the presence of Celts in the region is attested archaeologically, particularly through graves. Over the fourth century, Celtic influence spread south towards Greece. An embassy from one…
