The Black Sun fortress was a fortified compound built into a cliffside on the volcanic Outer Rim world of Mustafar. From within, a cabal of Falleen nobles led and operated the criminal syndicate known as the Black Sun during the Clone Wars. It was here that Darth Maul and the Death Watch Mandalorians confronted the Black Sun leadership with an ultimatum to join the Shadow Collective, a criminal alliance set up and led by Maul.