A small extremist Vulcan faction that wanted all outsiders expelled from Vulcan, and whose agent Tallera sought the ancient psionic resonator to enforce that aim.
The Vulcan Isolationist Movement is a fringe group who believe that contact with other species has polluted Vulcan culture, and that their world should withdraw from the Federation and remove every alien from its soil.
It lies behind the events of the Next Generation two-parter Gambit. A mercenary crew under Arctus Baran is looting archaeological sites for the pieces of the Stone of Gol, a weapon from Vulcan's violent past that kills by amplifying thought. Baran's Romulan-looking officer Tallera claims to be an agent of Vulcan security, but is in fact an isolationist named T'Paal.
On Vulcan she assembles the resonator and turns it on Picard, Riker and Worf. Picard has deduced that it has no effect on a mind empty of aggression, and it fails. She is arrested and the pieces destroyed.