Boii Boii (Latin plural, singular Boius; Greek ) is the Roman name of an Iron age tribe located at the beginning of their history in central Europe, perhaps in or including the regions that still bear their nameBavaria and Bohemia. The Roman and Greek historians of the late Roman Republic and Roman Empire considered them to be a Gallic or Celtic tribe; that is, a member of a larger ethnic group in Europe termed the Celts or Gauls.