Jedi Master Thon comes from an unknown system, deep within the Unknown Regions. His origins are as shrouded in mystery as much as his homeworld is. With so little information on Thon's species, the Republic's Bureau of Xenology gave Thon's species the arbitrary name of Wharl after all attempts by the Bureau to query Thon of his origins were refuted. Thon is actually a member of the Tchuukthai species and speaks their native language of the same name. Even still, the Tchuukthai are still as much an enigma as the Wharl. Thon's early career as a Jedi Knight is also mystifying as one day, Thon just arrived on the Jedi planet of Ossus already possessing great ability in the ways of the Jedi.
In turned out in fact, that Thon was able to teach the Jedi Masters on Ossus a few previously unknown powers. Thon spent a few more years on Ossus, but soon yearned for a more isolated planet, one where he could teach his apprentices in peace. Setting out in search of such a planet, Thon left Ossus with just a single lightsaber. As Thon traversed the galaxy, a point of complete blackness caught his interest. As his ship made its way towards that point of blackness, Thon meditated on its presence. Thon and his ship made their way to the planet Ambria, located within the Stenness Node, and the entire planet was permeated with the Dark Side. It turned out that during the fall of the Sith Empire a millennium before several Sith warriors had fled to Ambria during their retreat.
Although they passed into the Force centuries before Thon arrived, their spirits still haunted the remote world and had devastated it scourging it of almost all life, leaving it a desolate, bleak place. Thon decided it was here he was needed, and set down on the rocky surface. However, as soon as he left his ship he was attacked by the Sith spirits, which he repelled easily without much effort. But, as time went on, the constant attacks by the spirits left Thon weak and weary. In a final, desperate effort, Thon swam out into the planet's Lake Natth, and he pretended to surrender himself to the Dark Side. As the Sith spirits swarmed over him, Thon lashed out with a net of Light Side energy, ensnaring the Sith spirits capturing them and trapping them in Lake Natth forever.