Korriban was the homeworld of the Sith Species. After the Sith Species moved to Ziost, Korriban became a graveyard planet. Years later, a new Sith came to the planet. One with hopes of a new galaxy and the death of the Jedi. This Sith was Lord Revan. After the capture of a Stardestroyer, a base was made on the surface.
After a Kuat Space Yard was transferred to Coruscant, an academy was built in it. The academy was then moved to Korriban.