The Star Wars galaxy contains millions of planets and moons, so it's no surprise that several of them are filled with the light side or even enhance the dark side like Thule and Ziost. Dark side planets in particular serve as tools, headquarters, and homes for the Sith. Within the Legends continuity, the list includes worlds not present in canon as well as planets that do not outwardly display the darkness that permeates throughout.
Source：https://www.cbr.com/star-wars-legends-dangerous-planets/
