In the Farscape episode 'Throne for a Loss' (season one, episode four) The Trao are introduced as the first of their line is imprisoned with Rygel. It is explained by Jotheb that the Trao span many worlds (around 10,000) and have a population of approximately 40 trillion. Whenever Rygel says he's never heard of the Trao, Jotheb says that the imperfection is his which seems to imply that the Trao have also interacted with many other races.
As it seems they are at least as powerful as the Peacekeepers or the Scarrans so I'm wondering, where are the Trao after this episode and why don't we seem them again?
Please note that I'm looking for a in-universe answer.