Bolarus IX (also known as Bolarus, Bolius IX, or Bolias) was an M-class planet in the Bolarus system and was the homeworld of the Bolian race. It was a member of the United Federation of Planets. Important sites on Bolarus IX included the Cliffs of Bole and the Bank of Bolias. (DS9: "Invasive Procedures", "Who Mourns for Morn?")
Bolian territory was a hotbed between the Federation and the Dominion during the Dominion War. A front was established by the Sixth Fleet in 2374 to prevent Dominion forces from taking the Bolarus system and outlying colonies. Starfleet developed a new strategy during the war on the Bolian front which was known as the Bolian Operation. (DS9: "Behind the Lines", "The Reckoning", "Penumbra")
Milami Thall, as well as her four older brothers, were born on Bolarus IX.
Sileon Thall and his followers attempted to persuade the Bolian government to ease the "cultural contamination" Bolian society was undergoing when Bolarus IX and the Federation started seriously talking about Federation membership. The group started the Bolian Isolationist Movement. Sileon Thall and his followers (the Bolian Isolationists) either left or were expelled from Bolarus IX sometime between 2348 and when they founded New Bolarus around 2358.