For the mirror universe counterpart, see Klach D'Kel Bracht (mirror).
The Briar Patch (or Klach D'Kel Brakt) is a region of dangerous space matter created by the remains of supernovae and metaphasic radiation located in Sector 441, in the Alpha Quadrant. All vessels that enter the region must travel at reduced impulse power so that their impulse manifolds do not become overheated, and the use of warp drive is not an option.
In the 18th century, a group of Ba'ku arrived in the Briar Patch and established a colony on one of several planets located in the Patch. The planet contained metaphasic rings that meant that their lifespans were greatly increased. (TNG movie: Star Trek: Insurrection)
By the 22nd century, the Patch was located inside Klingon space, although they maintained no military presence inside. In 2154, Dr. Arik Soong viewed the area as a perfect hiding place for him and his Augments when they were being pursued by the Enterprise (NX-01). Upon seeing the Patch on the viewscreen he termed the name Briar Patch in relation to an old story from Earth. (ENT episode: "The Augments")
In 2256, the region's location was labeled on a tactical map on the bridge of the USS Discovery. (Star Trek DIS episode: "Choose Your Pain")
Later that year, this region's location was labeled on the star chart "Alpha/Beta Quadrant Overview" in the ready room aboard the USS Discovery. (Star Trek DIS episode: "Magic to Make the Sanest Man Go Mad")
Early in 2286, an incident occurred within the Briar Patch, involving the newly-launched USS Enterprise-A and a fleet of refugee Klingon freighters seeking a new home away from persecution in the Klingon Empire. An Imperial bird-of-prey under the command of Korgh sought to capture the lead freighter (commanded by a disgraced Klingon general) and kill Captain James T. Kirk, but the assassination plot was foiled thanks to the efforts of Captain Spock and the rest of the Enterprise crew. (ST - Prey novel: Hell's Heart)
By 2375, the Briar Patch was located inside Federation space, and was the setting for a joint Starfleet-Son'a mission in the Patch which was the forced relocation of the Ba'ku and attempt to harness the life-prolonging powers of the planet's rings. Thankfully, Captain Jean-Luc Picard and the crew of the USS Enterprise-E managed to prevent this. (TNG movie: Star Trek: Insurrection)
Following these events, Starfleet established Outpost 40 in the Patch and maintained a small task force to protect the Ba'ku planet and the immediate area. (TNG video game: Hidden Evil)
In 2376, the Patch was the site of a further battle between Starfleet and Son'a forces as they attempted to take control of the planet. (TNG video game: Armada)