The Osi or Osii were an ancient tribe dwelling north of the Marcomanni and Quadi, in a woody and mountainous country. Their national customs, as well as their language, were those of the Aravisci, who Tacitus called Pannonians. They were tributaries to the Quadi and Sarmatae. The exact districts they inhabited cannot be determined, nor do we know whether they had migrated from Pannonia, or whether they were an ancient remnant of Pannonians in those districts.
Tacitus described the Osi as living "behind" (Latin: retro) the Marcomanni, moving north from the river Danube. They were neighbours of the Marsigni, Gotini, and Buri.
- Behind them the Marsigni, Gotini, Osi, and Buri, close in the rear of the Marcomanni and Quadi.
Tacitus described them as a Germanic "natio", using that term in a geographical sense.
- Whether however the Aravisci migrated into Pannonia from the Osi, a German race , or whether the Osi came from the Aravisci into Germany, as both nations still retain she same language, institutions, and customs, is a doubtful matter; for as they were once equally poor and equally free, either bank had the same attractions, the same drawbacks.
In another passage, Tacitus explains that the Osi are nevertheless not really Germani according to Tacitus, who in this case uses language to distinguish them.
- the Marsigni and Buri, in their language and manner of life, resemble the Suevi.
- The Gotini and Osi are proved by their respective Gallic and Pannonian tongues, as well as by the fact of their enduring tribute, not to be Germans. tributa patiuntur.]
- Tribute is imposed on them as aliens, partly by the Sarmatæ, partly by the Quadi. The Gotini, to complete their degradation, actually work iron mines. All these nations occupy but little of the plain country, dwelling in forests and on mountain-tops.
References
This article incorporates text from a publication now in the public domain: Smith, William, ed. (1854–1857). "Osi". Dictionary of Greek and Roman Geography. London: John Murray.