The Yridians were a non-aligned species from the Alpha or Beta Quadrant.
Most Yridians encountered tend to be information merchants or smugglers, and, because of this, they were generally viewed as untrustworthy. (TNG: "The Chase"; DS9: "Facets")
Yridians invented a method based on the usage of gravimetric scanners to cheat at the dabo table. (DS9: "Nor the Battle to the Strong")
In 2342, the USS Beachmont rescued a Yridian freighter from a Cardassian attack. Commanding officer Paul Twining and an away team beamed over to the crippled freighter to find few survivors, including a Bajoran infant Twining and his wife eventually adopted: Russell Twining. (Star Trek: Pendragon)
Starfleet officer Rudolph Ransom made official first contact with the Yridians sometime in the mid-24th century. Prior to this, the Federation believed their race was extinct. (VOY: "Equinox")