Kejim served as the location for the Kejim Outpost, a base of the Empire Reborn. It was generally thought to be deserted after the first Death Star's destruction.
Following the Death Star's demise, the Imperial listening post ceased operations. However, during the era of the Empire Reborn, it reactivated, utilizing outdated Imperial codes. Although faint, these signals were picked up by the New Republic Intelligence's communications team, who then attempted to decode them.
This situation led Mon Mothma to dispatch the mercenary duo of Jan Ors and Kyle Katarn to the planet for investigation.
A partially successful decryption of the messages indicated they were seemingly addressed to Imperial Remnant Admiral Galak Fyyar, with mentions of the Valley of the Jedi and "Reborn." Katarn was hesitant to revisit a past trauma, so Mon Mothma incentivized him with double his standard pay. Ors swiftly accepted the offer on their behalf, thereby initiating a series of events that would dramatically alter Katarn's life and ultimately neutralize a significant threat to the Jedi and the New Republic's safety.
Upon his exploration of the Imperial outpost, Katarn realized the site was indeed inhabited once more. Delving deeper into the base, he came across a laboratory where peculiar medical experiments were being conducted, employing high-energy equipment and unknown crystals.
The truth later came to light: Admiral Fyyar, collaborating with the Dark Jedi Desann, was utilizing the laboratory to experiment with imbuing subjects who possessed minimal or no natural Force-sensitivity with Force abilities. This was achieved using Artusian crystals as part of Hethrir's Empire Reborn initiative. Ultimately, Kyle Katarn destroyed the Kejim laboratory by detonating a bomb.