However, by the time their territory was annexed by Rome under founder-emperor Augustus (16 BC), they had become largely Celtic-speaking[citation needed] through contact with neighbouring peoples such as the Vindelici.

Finally, during the centuries of Roman rule, they became Latin speakers: their distinctive provincial patois survives today in the form of the Rhaeto-Romance languages[citation needed].

According to Holder, a total of 12 Raetorum cohortes appear to have been raised, 10 of them not later than the rule of Claudius (41-54) and 2 shortly after 70 AD.

[4] The unit in Raetia, the subject of this article, is denoted simply cohors I Raetorum as there is no evidence it was equitata.

It is attested by an undatable tile stamp in the Roman fort at Schierenhof in Schwäbisch Gmünd (Gamundia Romana), which may have been one of its bases.