The Karlon were a warp-capable species from the Delta Quadrant. The Karlon were known to be tenacious in battle but the power and range of their weapons were limited. In the early 2380s, the Karlon joined the interstellar Kinara alliance. (VOY novel: Acts of Contrition)
In February 2382, three Karlon ships were part of a nine-ship Kinara fleet blockading the Gateway. When negotiations between Worlds presider Isorla Cin and the Kinara broke down, a battle ensued between the Kinara and their Voth allies, and the Confederacy and their Federation allies. At least one of the Karlon ships was destroyed. The battle ended when Federation Vice Admiral Kathryn Janeway turned herself over to Kinara authorities to stand trial.
This occasion marked the first contact between the Karlon and the Federation. The Karlon were identified by General Deonil of the CIF Sixteenth Hadden. Captain Regina Farkas of the USS Vesta had Lieutenant Jepel Omar add the specs of their vessels to the Starfleet database. (VOY novel: Acts of Contrition)