Theodore Musachi or Teodor II Muzaka or Musa Arbanas was member of Albanian noble family Muzaka who ruled the Principality of Berat. According to the chronicle of Gjon Muzaka (not very reliable primary source) Teodor II Muzaka participated in the Battle of Kosovo in 1389 together with Prince Marko. Teodor II Muzaka actually was in territorial dispute over Kostur with Prince Marko and because this dispute he was commemorated in Serbian epic poetry as Musa Kesedžija.
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Teodor II Muzaka Wikipedia(Text) CC BY-SA