Little is known of the origin or history of the Raetians, who appear in the records as one of the most powerful and warlike of the Alpine tribes. Livy states distinctly (v. 33) that they were of Etruscan origin (a view favoured by Niebuhr and Mommsen). A tradition reported by Justin (xx. 5) and Pliny the Elder (Naturalis Historia, iii. 24, 133) affirmed that they were a portion of that people who had settled in the plains of the Po and were driven into the mountains by the invading Gauls, when they assumed the name of "Raetians" from their leader Raetus; a more probable derivation, however, is from Celtic rait (mountain land). Even if their Etruscan origin be accepted, at the time when the land became known to the Romans, Celtic tribes were already in possession of it and had amalgamated so completely with the original inhabitants that, generally speaking, the Raetians of later times may be regarded as a Celtic people, although non-Celtic tribes (Lepontii, Euganei) were settled among them. The Raetians are first mentioned (but only incidentally) by Polybius (xxxiv. 10, iS), and little is heard of them till after the end of the Republic. There is little doubt, however, that they retained their independence until their subjugation in 15 B.C. by Tiberius and Drusus (compare Horace, Odes, iv. 4 and 14).

At first Raetia formed a distinct province, but towards the end of the 1st century A.D. Vindelicia was added to it; hence Tacitus (Germania, 41) could speak of Augusta Vindelicorum (Augsburg) as "a colony of the province of Raetia". The whole province (including Vindelicia) was at first under a military prefect, then under a procurator; it had no standing army quartered in it but relied on its own native troops and militia for protection.

Map of Rhaetia

The famous Roman limes ran through much of Rhaetia: for more information see The Roman Frontiers.