The Fnth (pronounced "FAY-noth") were a humanoid species from a planet in the Gulkhana sector. (Ship Recognition Manual, Volume 2: Starships of the Cardassian Union)
The Fnth had long, cylindrical heads that descended into their chest cavities. Their arms and legs had two joints and their digits resembled think cloth rather than fingers. Due to their large head and chest cavity it allowed them to produce and hear a much wider range of sounds than most humanoids. Their alphabet was made up of over 200 letters, each represented by a distinct tone, which made their speech seemed more like music than conversation.
The Fnth had developed into a spacefaring race several centuries prior to the 24th century when they made first contact with the Cardassian Union. Their own expansion was seen as a threat by the Cardassians, who went to war against the Fnth and conquered them. Over time the Fnth became a loyal member of the Union and were even permitted to field their own starships (under strict Central Command authority). However, following the end of the Dominion War and the devastation to the Cardassian Union rumblings of independence once again circulated among the Fnth.