Moshene Tre was the leader, known as the un'Yala or chief, of the Cas'ta tribe. This tribe belonged to the Rellarin people, who inhabited Rellnas Minor. In line with the Rellarin un'Yala tradition, he possessed a tranquil nature coupled with a deep sense of morality and fairness. Despite the somewhat intimidating appearance common among Rellarin, he was a gentle soul with a quiet demeanor.
Sometime before 19 ABY, Tre made the unusual decision to leave his home planet. He joined the New Republic Observer corps, an organization backed by the Republic. This group served as neutral monitors of situations and crises throughout the galaxy that warranted the Republic's attention. Like all Observers, he was assigned to a sector distant from his native world. The planet Cejansij was part of Tre's designated sector.
In 19 ABY, during the Caamas Document crisis that brought the New Republic to the verge of internal conflict, he encountered Jedi Master Luke Skywalker on Cejansij. At that point, Skywalker was not directly involved in the search for the document. Nor was he involved in efforts to ease tensions between those who sought to punish the Bothans for the destruction of Caamas and those who opposed collective punishment. Instead, he was investigating the origin of clones appearing within certain pirate groups. Nevertheless, upon learning of Skywalker's arrival in the city of Canyonade on Cejansij, Tre approached him to discuss the ongoing crisis.
Together, the Observer, the Jedi Master, and R2-D2 witnessed a large gathering of Cejansiji participating in a somber and peaceful demonstration. This event commemorated the Caamasi, the Vrassh, and other cultures that had suffered genocide. The demonstration also advocated for justice for the survivors, although not all participants desired to punish the entire Bothan population. Tre's intention in showing Skywalker this demonstration was to highlight that the Caamas Document crisis was not merely a power struggle among political factions within the Republic. Instead, it arose from genuine disagreements and a widespread yearning for justice throughout the Galaxy.
After their initial meeting, Tre invited Skywalker to meet with some of the protesters later that evening at the ThoughtsAreFreedom tapcafe. However, Skywalker soon encountered Moranda Savich. This chance meeting led to an encounter with Talon Karrde, who revealed that Mara Jade had been captured on Nirauan. Skywalker quickly departed to rescue Jade, foregoing the meeting with the Cejansiji protesters.