By 390 BC, several Gallic tribes had begun invading Italy from the north as their culture expanded throughout Europe. Most of this was unknown to the Romans at this time, who still had purely local security concerns, but the Romans were alerted when a particularly warlike tribe, the Senones, invaded the Etruscan province of Siena from the north and attacked the town of Clusium, not far from Rome's sphere of influence. The Clusians, overwhelmed by the size of the enemy in numbers and ferocity, called on Rome for help. Perhaps unintentionally the Romans found themselves not just in conflict with the Senones, but their primary target. The Romans met them in pitched battle at the Battle of the Allia around 390–387 BC. The Gauls, under their chieftain Brennus, defeated the Roman army of around 15,000 troops and proceeded to pursue the fleeing Romans back to Rome itself and partially sacked the town before being either driven off or bought off. They were probably defeated by the exiled dictator Marcus Furius Camillus who gathered the scattered Roman forces that consisted partly of fugitives and partly those who had survived the battle of Alia, and marched to Rome. According to tradition, he took the Gauls by surprise, when Brennus, having tricked the weights in which the gold rescue that had been set for the city was measured, uttered the expression Vae Victis! (Woe to the losers!); Camillus claimed that, since he was a dictator, no agreement was valid without his acquiescence, so no ransom was due and he answered Breno with another famous phrase Non auro sed ferro liberanda est patria (It is with iron, not with gold, how the homeland is released). After defeating the Gauls in the subsequent battle, he entered the city in triumph, greeted by his fellow citizens as alter Romulus (the other Romulus), pater patriae (father of the homeland) and conditor alter urbis (second founder of the city).