The Voss people come from a neutral system led by Force-sensitive Mystics. The planet was discovered by the wider galaxy during the Galactic Cold War, and both the Galactic Republic and the Sith Empire pursued diplomatic channels to convince the Voss to join their factions.
This player character outfit is wearable is based upon robes worn by Voss leaders and dignitaries. Screenshots of the “Voss Dignitary” armor are from Swtorista. 3D turn-arounds of similar Voss NPC outfits can be found at Jedipedia.