Context: Roman–Gallic wars
Over the course of nearly four centuries, the Roman Republic fought a series of wars against various Celtic tribes, whom they collectively described as Galli, or Gauls. Among the principal Gallic peoples described as antagonists by Greek and Roman writers were the Senones, Insubres, Boii, and Gaesatae.
The Romans first came into conflict with Gauls who entered Italy from the north. Some of these settled in the lands immediately south of the Alps, which became known as Cisalpine Gaul: "Gaul this side of the Alps". Gaulish armies, some perhaps fighting as mercenaries in the service of the cities of Magna Graecia, plundered territory in Etruria and Latium during the fourth century, famously sacking Rome circa 390 BC.
