House Thul is one of the Alderaanian Noble Dynasties. Originally, it had been exiled from the Alderaanian Parliament. However, with Imperial support, House Thul returned to power and brought Imperial personnel to Alderaan to help "reestablish its estates".
This lore can be found on Alderaan. There is a banner outside of a phased building in the Organa Vinerium.
- "The members of House Thul are descended from a wealthy and ambitious merchant who bought his way into the nobility. The Thuls considered this a point of pride, specializing in brokering trade and acting as caretakers of Alderaan’s economy–yet for generations, the relative youth of the Thul house carried a stigma. Unable to marry a Thul into royalty, the house made a desperate bid for the throne–Thuls switched an Organa infant with a Thul baby and supported the changeling as a potential bride for the crown prince. A young Jedi exposed the treachery and stopped the wedding, creating a scandal that led to the disgraced Thul’s exile from Alderaan. Thul maintained its pride and its culture in exile, though the house became impoverished and isolated in its offworld estates. It was decades before Thul nobles were contacted by the Imperial Diplomatic Service; the Empire promised to restore Thul to its rightful glory, to train its soldiers and educate its children and one day help it return to Alderaan. At last, in the aftermath of Alderaan’s withdrawal from the Republic and the death of its queen, a generation of Thuls raised alongside the Empire came home–eager to restore the family name and take vengeance against Thul’s enemies. Thul has already gained the allegiance of a number of lesser houses, and with Imperial support stands as a true contender for the throne."
- ―In-game Codex (Organizations)