The Treasury Guard was the defense force of the Ferengi Alliance.
In 2376, the Treasure Guard led the defense of Ferenginar against an Orion attack. (TNG novel: Doors Into Chaos)
Following the Ferengi entry into the Khitomer Accords, Treasury Guard personnel were assigned to Starfleet starships. (ST - Typhon Pact novel: Plagues of Night)