Relus, situated in the Deep Core, held the position of the fourth planet in the Beshqek system. It was one of the two terrestrial planets present in the system and had one moon in orbit around it.
Following the calamitous destruction that befell Relus' adjacent planet, Byss, in the year 11 ABY, the man-made hyperlane known as the Byss Run, which linked the Beshqek system to the Core Worlds, started to break down. Millions of Relus's populace escaped to Prakith and other locations, trying to avoid being stuck in the system. Nonetheless, it was thought that millions more were stranded on Relus when the Byss Run gave way entirely, rendering the Beshqek system nearly inaccessible.
The initial mention of Relus occurred in the Byss and the Deep Core article from Planet Hoppers, penned by Rodney Thompson in 2005, which was the first to pinpoint each of Byss's neighboring planets within the Beshqek system. Later, the planet's fate became interwoven with Byss's annihilation in The Essential Atlas, a reference book from 2009 authored by Daniel Wallace and Jason Fry.