The Bolian Isolationist Movement was a movement by a minority of Bolians to stop Bolarus IX's involvement with other races. Sileon Thall was one of the group's founders and leaders.
Bolian Isolationists felt the Bolian government was contaminating their culture by involvement with the Federation and Bolian talk of applying for Federation membership. Further discontent came with each conflict the Bolians and Moropa had.
The friction between the Isolationists and Bolian government to a head sometime after 2348, and many members of the Bolian Isolationist Movement, gathered with their friends and family, left Bolarus IX to find a new, isolated planet to colonize and follow their vision, true to Bolian customs and history.
The Isolationists' departure supposedly ended the movement on Bolarus IX, but some Bolians, even in 2372, felt strongly about the issue. USS Cantabrian doctor Akeras Pela refused to operate on Isolationist leader Sileon Thall's daughter, Starfleet lieutenant Milami Thall, despite a direct order from her superior, Dr. Marie Bourget. (Star Trek: The Cantabrian Expeditions: "Oh, What A Lovely War", "Howl")
- According to the backstory, the Bolian government's official line was the Bolian Isolationists were exiled from Bolarus IX, instead of being incarcerated for their crimes. The Isolationists' official story was they left Bolarus IX voluntarily as to halt what they perceived to be any further cultural contamination.