The Nihil marauders were anarchistic marauders who were most prominent during the High Republic era. Their 'Great Hall' was based in No-Space, an area of the galaxy unknown to everyone but the Nihil. They utilised a fleet of starships to wreak havoc in their raids (mostly in the Outer Rim). This information is from the High Republic comics, and now I'm discussing about their mention in Star Wars Jedi: Survivor, where they were mentioned when speaking to Eno Cordova.
Emergences were disasters that occurred as an aftermath of the Great Hyperspace Disaster, where the Legacy Run was ripped apart and thrown across the galaxy at extreme speeds. These Emergences were capable of causing extreme damage to the celestial objects they collided with, one of which destroyed the Shattered Moon of Koboh.
*I thought it was nice to find out what happened to the moon. However, what impact it had is IMPORTANT to the Jedi: Survivor storyline.*
At the time of these Emergences, the Nihil were raiding the Jedi on Tanalorr, which was recently discovered by Dagan Gera. They had found Tanalorr, most likely via the compasses on Koboh. While being pressured by the raids, the debris of the Shattered Moon crashed into Koboh, causing the Jedi to abandon both Koboh and Tanalorr.
*It's awesome to learn more about these enigmatic, dangerous marauders, especially in Jedi: Survivor, which already has an awesome storyline. Why am I making this post? I wanted to share how important they are in this game's storyline, and how I'm hoping for the Nihil to be even more prominent in the next instalment. I think we should learn even more about these marauders.