Sector Four was a region of realspace that the Confederacy of Independent Systems governed throughout the Clone Wars conflict with the Galactic Republic. By the year 22 BBY, Sector Four was chosen as the location for a clandestine Separatist base. At this base, General Grievous, a Kaleesh military leader, intended it to be a meeting place for the Subjugator-class heavy cruiser named Malevolence. Nevertheless, prior to the Malevolence's arrival at Sector Four and the Separatist base, Republic forces obliterated it during the Battle of the Kaliida Nebula.
The initial reference to Sector Four occurred in the Star Wars: The Clone Wars television show's first season episode titled "Destroy Malevolence," which was the fourth episode overall and was broadcast on October 17, 2008.