at this point, the brotherhood of darkness, arose, lead by the sith lord skere kaan. they focused on controlling the infighting between the sith. this policy allowed them to make great progress in their war against the republic. ironically, one of their own, a sith lord by the name of bane turned on them, because he disapproved of their methods. he manipulated the brotherhood into extinction, and they were defeated. bane started the rule of two, which evolved into the sith as they are seen in the films.