The Grumani believed that moral conduct had to be derived from the directives of Mani, the founder of their religion, as interpreted by Mani's Hierophants.
The Grumani split from the breakaway Spumani in a relgious schism, resulting in a conflict that was fought between the two sects for eight hundred years, until the arrival of the Sith in the Grumani sector during the New Sith Wars. Tenisons between the two groups later cooled to merely mutual disdain.