Around 390 BC, the Gallic chieftain Brennus and his troops made their way to Italy through the Alps, defeated the Romans in the Battle of the Allia, and besieged and ransomed Rome. The Gallic invasion left Rome weakened, and the Gauls continued to harass the region until 345 BC when they entered into a formal peace treaty with Rome. But the Romans and the Gauls would remain adversaries for the next centuries, and the Gauls would continue to be a threat in Italy.