The Teutons (Teutones, Teutoni, Τεύτονες) were an ancient northern European tribe mentioned by Roman authors. The Teutons are best known for their participation, together with the Cimbri and other groups, in the Cimbrian War with the Roman Republic in the late second century BC. Julius Caesar described them as a Germanic people, a term he applied to all northern peoples located east of the Rhine, and later Roman authors followed his identification. On one hand, there is no direct evidence about whether or not they spoke a Germanic language, and evidence such as their name and the names of their rulers indicates at least a strong influence from Celtic languages. On the other hand the indications that classical authors gave about the homeland of the Teutones is considered by many scholars to show that they lived in an area associated with early Germanic languages, but not in an area associated with Celtic languages. The ethnonym is attested in Latin as Teutonēs or Teutoni (plural) or, more rarely, as Teuton or Teutonus (singular). It transparently derives from the Proto-Indo-European (PIE) stem *teuteh2- ('people, tribe, crowd') attached to the suffix -ones, which is commonly found in both Celtic (Lingones, Senones, etc.) and Germanic (Ingvaeones, Semnones, etc.) tribal names during the Roman era. The stem apparently had a lower-class connotation, as opposed to an elite group or a ruling class and its original meaning in PIE times may have been 'the people under arms', as suggested by the Hittite tuzzi- and the Luwian tuta ('army'). Thus, the name Teutones may be interpreted as deriving from Proto-Celtic *towtā ('people, tribe'), or it may have been from a stage of Germanic language development prior to the first consonantal shift ("pre-Germanic") (compare the later form *þeudō- 'nation, people, folk'; cf. Gothic þiuda). A possible corruption of the original name by Greek and Latin writers makes the attribution less secure. The much later use of Teuton to refer to speakers of West Germanic languages occurred in the Latin of monastic writers by the ninth century and has continued into modern times.