The Gorlan were once subjects of the Terran Empire. In 2155 the Imperial Starfleet starship ISS Enterprise visited a station in their system before proceeding to rendezvous with an Imperial assault fleet. (ENT: "In a Mirror, Darkly")
In the 23rd century, the Gorlan were involved in an uprising against the Empire. They were presumably wiped out when James T. Kirk, in one of his first acts as captain of the ISS Enterprise, destroyed their homeworld to suppress the uprising. (TOS: "Mirror, Mirror")