Latin League, an alliance of Latin communities that formed in opposition to Etruscan Rome at the end of the 6th century bc. By that time the Etruscan rulers of Rome had established a de facto hegemony over the Latin communities south of the Tiber River, a situation accepted in Rome’s treaty with Carthage of 509 (reported by the Greek historian Polybius). With the fall of the Etruscan monarchy, the villages of Latium formed an alliance, centred at Aricia, which modern scholars call the Latin League. Rome fought the Latin cities at the Battle of Lake Regillus (499 or 496), and the consul Spurius Cassius Vecellinus made a treaty with the Latins on an equal basis for mutual defense (493). As Rome gained territory, the political power of the league diminished. The treaty was renewed in 358 with changes that secured Rome’s leadership. This led to an outbreak of war from which Rome emerged victorious in 338, when the Latin League was dissolved.