The sources whence it was formed were of course the same as they are everywhere.
Isolated names like those of the kings Numa, Ancus, Tullus, to whom the clan-names were probably only assigned subsequently, and isolated facts, such as the conquest of the Latins by king Tarquinius and the expulsion of the Tarquinian royal house, may have continued to live in true general tradition orally transmitted.

Further materials were furnished by the traditions of the patrician clans, such as the various tales that relate to the Fabii.

Other tales gave a symbolic and historic shape to primitive national institutions, especially setting forth with great vividness the origin of rules of law.

The sacredness of the walls was thus illustrated in the tale of the death of Remus, the abolition of blood-revenge in the tale of the end of king Tatius( 15), the necessity of the arrangement as to the -pons sublicius- in the legend of Horatius Cocles,( 15) the origin of the -provocatio- in the beautiful tale of the Horatii and Curiatii, the origin of manumission and of the burgess-rights of freedmen in the tale of the Tarquinian conspiracy and the slave Vindicius.

To the same class belongs the history of the foundation of the city itself, which was designed to connect the origin of Rome with Latium and with Alba, the general metropolis of the Latins.