 According to Szadeczky-Kardoss, many of the titles and ranks used by the Pannonian Avars were also used by the Turks, Proto-Bulgars, Uighurs and/or Mongols, including "khagan" (or "kagan"), "khan, kapkhan, tudun, tarkhan", and "khatun".There is also evidence, however, that ruling and subject clans spoke a variety of languages.Proposals by scholars include Caucasian, Iranian, Tungusic, Hungarian and Turkic.