Ziost

Ziost (pronounced /ziɒst/), referred to as the "Gateway to the Empire" during the Galactic War, was a rocky world—and potent focal point of the dark side of the Force—located in the Ziost system, a star system in the Sith Worlds region of the Outer Rim Territories' Esstran sector. It was connected to other nearby worlds by the Nache Bhelfia hyperlane. Ziost was also the one of the primary adopted homeworlds of the Sith species, considered one of the five sacred Sith planets, and served as the capital of Adas's Sith Empire and the Old Sith Empire. The Sith species ended up leaving their desolate homeworld Korriban as a vast tombworld after the death of their leader, Adas.

Historically a lush, densely-forested world with a warm climate, Ziost endured an ice age at some point after 27,700 BBY, after many of the Sith had arrived, including (but not limited to) Kissai priest and Massassi warrior castes. As a result, the planet was transformed into a vast, bitterly-cold tundra with a dry atmosphere—essentially a frozen desert—and hardly any precipitation.

Eventually, Ziost became a major Sith buffer-world during the days of Vitiate's Sith Empire, before being forgotten entirely.

Text and facts from the “Ziost/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.