The Helvets (Helvetii in Latin) was the name for some Celtic tribes who inhabited the Swiss Plateau some centuries before the era. The names of some of these tribes are known, including the Tigurini, Ambrones, Verbigeni and Tugini. The Rauraci and Suebi inhabited the regions of Basel, Southern Alsace and Baden in the same period. The other tribes in present-day Switzerland and neighbouring areas are: Nantuates in Chablais, Veragri in the Martigny region, Seduni in the central part of Wallis, Raetii in the Grisons valleys and the area around St. Gallen, the Lepontii in Ticino, the Salassi in the Valley of Aosta and the Allobroges in Geneva (Roman territory from 122 B.C.). This information about the Celts comes from Roman and Greek authors and archaeology. The Celts had no written culture. The (high) culture, settlements (called oppidum/oppida by Caesar) and Celtic societies, including the Helvets, are far better known nowadays through archaeology.
The Bello Gallico by Julius Caesar (100-44 BC) describes the history of the Helvets, their migration and defeat against the Romans in 58 B.C. at Bibracte (near the city of Autun). The first testimony of the Helvets dates from the end of the 4th century B.C., however. A mention on a vase reads as Helvets. The first concrete date and the first historical Helvetic name is the battle of Agen in 107 B.C. and Divico as captain of the Tigurini, who crushingly defeated the Roman legions. The Helvets are presented by Caesar as the most powerful of the Celtic peoples. His information provides an insight into their (Celtic) society. Like Greek and Roman civilization, it was based on slavery, aristocracy, an oligarchic system and warlords. The Druids organized the religion. Today, around fifteen oppida on the current Swiss territory have been discovered, most of them in the Swiss Plateau (Mont-Vully, Lausanne, Roggwil, Bern, Luzens, Basel (murus gallicus), Jensberg, Bois de Châtel, Sermuz, Yverdon, Üetliberg, Windisch, Rheinau, Zürich, Altenburg). The course of history after the defeat in 58 B.C. is Roman and the centuries of Aventicum as capital of the Helvets and Romanization would begin, in particular after the Roman conquest in 13 B.C. (Source: G. Kaenel, L’an, -58. Les Helvètes. Archéologie d’un peuple celte, Lausanne 2012).