Around 390 BC, the Gallic chieftain Brennus made his own way through the Alps, defeated the Romans in the Battle of the Allia and sacked Rome for several months. The Gallic invasion left Rome weakened and encouraged several subdued Italian tribes to rebel. One by one, over the course of the next 50 years, these tribes were defeated and brought back under Roman dominion. Meanwhile, the Gauls would continue to harass the region until 345 BC, when they entered into a formal treaty with Rome. But Romans and Gauls would maintain an adversarial relationship for the next several centuries and the Gauls would remain a threat in Italia.