Helvetii

When those formidable Helvetii marched out of their Alpine cantons to occupy Gallic lowlands in 58 BC, Caesar deployed geopolitics to defeat them -- seizing strategic terrain, controlling their grain supplies, and manipulating rival tribes.

“Of all these, the Belgae are the bravest, because... they are the nearest to the Germans, who dwell beyond the Rhine, with whom they are continually waging war; for which reason the Helvetii also surpass the rest of the Gauls in valor, as they contend with the Germans in almost daily battles.”

Instead of enslaving the vanquished Helvetii as other Roman generals might have, Caesar, mindful of the empire’s geopolitical balance, returned them to their homelands with generous provisions, lest the German “barbarians” cross the Rhine and destabilize Gaul’s natural frontier.

There you’ll find an amphitheater built when the 2,000-year-old town was known as Aventicum, the Roman capital city of the Helvetii people.

The reports of gold and plunder spread by the Cimbri and Teutones on their way to southern Gaul induced the Helvetii to follow their example.