The national history, however, furnished the theme of the Brutus and Decius, - the expulsion of the Tarquins and the self-sacrifice of Publius Decius Mus the younger.
Lucius Junius Brutus, her husband's cousin, put himself at the head of the people, drove out the Tarquins, and established a republic. The accounts of this tradition in later writers present many points of divergence.
After the expulsion of the Tarquins the chief events in Etruscan history are the vain attempt to re-establish themselves in Rome under Lars Porsena of Clusium, the defeat of Octavius Mamilius, son-in-law of Tarquinius Superbus, at Lake Regillus, and the treaty with Carthage.
It first appears in Roman history at the end of the 7th century B.C. when it joined the other Etruscan towns against Tarquinius Priscus, and at the end of the 6th century B.C. it placed itself, under its king Lars Porsena, at the head of the attempt to re-establish the Tarquins in Rome.
Arretium appears as one of the cities which aided the Tarquins after their expulsion.
But when these families had expelled the Tarquins, and formed themselves into an exclusive aristocracy of privilege, the inconsistency between partial privilege and full burdens came to be strongly felt by the plebeians.