System J-25 was a planetary system that had at least six planets, located outside Federation space. As of 2365, the nearest Federation starbase to this system was Starbase 185; a Galaxy-class starship at maximum warp would require two years, seven months, three days, and eighteen hours away to reach it from J-25. Jouret IV, one of the outermost colonies of the Federation, was located over 7,000 light years away.
In 2365, the Borg still had a presence in the system. A Borg cube detected the Federation starship USS Enterprise-D when it was transported to this system by Q that year. Shortly afterward, the cube attacked the Enterprise-D and pursued it across the system before the Starfleet vessel was rescued by Q.
After the Borg incident, Commander William Riker wrote reports about the event and what was learned from surveys of the system and its planets. These reports became known to Shelby who was tasked with the Borg tactical analysis six months before the Battle of Wolf 359. (TNG: "The Best of Both Worlds")