The Osi or Osii were an ancient tribe dwelling beyond the Quadi, in a woody and mountainous country. But their national customs, as well as their language, were those of the Aravisci, who Tacitus called Pannonians. They were, moreover, tributary 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 wrote: ...and...