Order of the Sith Lords

After the devastating Seventh Battle of Ruusan, The last surviving Sith Lord, Darth Bane, reinvented the Sith Order into an organization based on stealth and secrecy after the Sith defeat on Ruusan. He founded the Rule of Two that would allow his eventual successor, Darth Sidious, to finally triumph over the Jedi and the Republic 1,000 years later.