The Vulcans were a close-minded species, originating on the planet Vulcan. They possessed a telepathic ability that could be employed to control the minds of others. This ability was exploited by the Terran Empire after the Empire conquered the Vulcans sometime after 2063. (IAMD)

After the Vulcan Spock was influenced by the mirror universe counterpart of James Kirk, he rose to power in the Empire and effected several reforms that eventually weakened it so significantly that it was easily crushed by the Alliance. (MM, CO)