The Cimbrian threat, along with the Jugurthine War, allegedly inspired the putative Marian reforms of the Roman legions, a view now contested by modern historians.

[1] According to some Roman accounts, sometime around 120–115 BC, the Cimbri left their original lands around the North Sea due to flooding (Strabo, on the other hand, wrote that this was unlikely or impossible[2]) They supposedly journeyed to the south-east and were soon joined by their neighbours and possible relatives the Teutones.

The following year the Roman consul Gnaeus Papirius Carbo led the legions into Noricum, and after making a show of force, took up a strong defensive position and demanded that the Cimbri and their allies leave the province immediately.

That same year, they defeated another Roman army at the Battle of Burdigala (modern day Bordeaux) and killed its commander, the consul Lucius Cassius Longinus Ravalla.

The Battle of Arausio was the costliest defeat Rome had suffered since Cannae and, in fact, the losses and long-term consequences were far greater.

Theodor Mommsen speculatively describes their methods of war: Their system of warfare was substantially that of the Celts of this period, who no longer fought, as the Italian Celts had formerly done, bareheaded and with merely sword and dagger, but with copper helmets often richly adorned and with a peculiar missile weapon, the materis; the large sword was retained and the long narrow shield, along with which they probably wore also a coat of mail.

The constitution was ignored and Gaius Marius, the victor over Jugurtha of Numidia was elected consul for an unprecedented, and arguably illegal, five years in a row, starting in 104 BC.

Because of the destruction of the Roman force at Arausio and the pressure of the impending crisis, Marius was tasked with rebuilding, effectively from scratch, the Gallic legions.

By 102 BC, Marius was ready to face the Cimbri; the latter, after difficulties in Spain, had turned north into Gaul, where they were joined by the Teutons.

[8] Marching south through Switzerland and Savoy, their army was augmented by some tribes of Helvetians, particularly the Tigurini, and the Ambrones of uncertain descent.

[9] When Marius heard of their movements, he advanced to Valence, and established his camp at the confluence of the Isère and the Rhône, where he could observe and halt the march of the Teutons.

So enormous were their numbers, that they reportedly took 6 whole days marching by his camp, and in their arrogance they taunted the Romans, what message they wished them to give to their wives?

For the first time they penetrated through the Alpine passes, which Marius's co-consul for that year, Quintus Lutatius Catulus, had failed to fortify, into northern Italy.

It would be at Vercellae near the confluence of the Sesia River with the Po on the Raudine Plain where the superiority of the new Roman legions and their cavalry were clearly demonstrated.

Their allies, the Boii, with whom they intermixed, settled in southern Gaul and Germania and were there to welcome and confront Julius Caesar, Marius's nephew, in his campaigns of conquest.