The Battle of the Allia was fought between the Senones, one of the Gallic tribes which had invaded northern Italy, and the Romans. It was fought at the confluence of the rivers Tiber and Allia, eleven Roman miles north of Rome. The Romans were routed and subsequently the Senones sacked Rome. The common date given for the battle is 390 BC. This is based on the account of the battle by the Roman historian Livy (Titus Livius) and the Varronian Chronology, a Roman dating system. Following the ancient Greek historian Polybius, who used a Greek dating system, instead, yields 387/6 BC.Tacitus said that the battle took place the 15 before the Kalends of August, which is 18 July.