Trelka was a star system located in the 24th century boundaries of the Cardassian Union.
Trelka was attacked by the Klingon Empire in the early 2330s, around the year 2333. Although the system was attacked by the Klingons, the High Council disavowed that they had ordered it. (ST - The Lost Era novel: The Art of the Impossible)
In 2360, a Cardassian cruiser approaching the Trelka system suffered a warp injector failure. (TNG novel: The Buried Age)
During the Dominion War, Trelka V was the location of a Dominion base that General Martok and his Klingon forces attacked in 2375. (DS9 episode: "Once More Unto the Breach")