The Talosian system was an inhabited planetary system in the Talos star group. It was a binary system with eleven planets. One of the planets, Talos IV, was inhabited by the Talosians, a technologically advanced telepathic species. (TOS: "The Cage")
Long range scans made by the United Federation of Planets of the system in the 23rd century showed that it was similar to the Sol system. Prior to 2236, this system had not been explored. In that year, the survey ship SS Columbia, while surveying the system, crash-landed on Talos IV. There was only one survivor from the crash, Vina.
In 2254, eighteen years later, the USS Enterprise discovered the fate of the Columbia after being lured to the system by a faked distress call. After escaping the Talosians, the crew recommended that the planet be placed under quarantine, a recommendation that Starfleet Command endorsed. General Order 7 was created to prohibit contact between the Talosians and Federation starships.
In 2267, thirteen years later, the Enterprise returned to the system to deliver a physically disabled Captain Christopher Pike to the care of the Talosians. (TOS: "The Cage", "The Menagerie, Part I", "The Menagerie, Part II")
In 2293, the location of Talos in the Milky Way Galaxy was labeled in a star chart that was in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country okudagram)