Sometime around 20 BBY, Jedi Grand Master Yoda traveled to Korriban and entered the tomb of the long deceased Bane. Bane awoke, appearing as a giant, smoldering specter out of his sarcophagus, and challenged Yoda, asking whether the Jedi had come to learn as his apprentice. Yoda said that Bane was an illusion, at which point the specter disappeared into the sarcophagus.
Bane's body had been obliterated when he failed to take over the body of his apprentice, Darth Zannah, and his spirit was consigned to Chaos, leaving just his arm which had been cut off shortly before his death.