Ziost, a planet situated within the Outer Rim Territories of the galaxy, could be found at grid coordinates R-4 on the Standard Galactic Grid. Notably, it held significance as one of the ancient worlds associated with the Sith.
According to the writings of the Jedi author Kli the Elder in the Rammahgon, Ziost was once a world boasting a flourishing environment. However, this changed when the Sith established their presence, leading to the planet's devastation, a fate it shared with worlds like Moraband, Exegol, and Asog. During the time of the Galactic Republic, Ziost, alongside places such as Malachor, Jaguada, and Rhelg, was placed under quarantine, and its Sith connections were deliberately obscured from historical records.
The original location of an ancient Sith ritual altar that later appeared in the Grand Republic Medical Facility on Coruscant in 19 BBY was Ziost. Sometime in the period between 0 BBY and 4 ABY, CR-8R regarded Fortress Vader on Mustafar as the most unsettling Imperial stronghold, second only to Ziost.
The planet Ziost made its debut in the new Star Wars canon through a galactic map featured in the Star Wars: The Force Awakens Beginner Game. This boxed set, part of Fantasy Flight Games' Star Wars Roleplaying series, was released in 2016. Within the Star Wars Legends continuity, Ziost was first presented as the capital world of the Sith Empire in the third issue of the Tales of the Jedi: The Golden Age of the Sith comic miniseries. This comic, penned by Kevin J. Anderson and published by Dark Horse Comics, was released on December 11, 1996.