It was not until Supreme Chancellor Pultimo ordered a counterinvasion of the region in the aftermath of the Great Hyperspace War that the Caldera failed to shelter the Sith.
It was far easier pass through the Caldera from the outside into Sith Space than the other way around, which brought a variety of beings into Sith Space during the time of the Sith Empire, such as Humans from the Tapani sector, and other various aliens such as the Houk. These people were integrated into the Sith society.
The Stygian Caldera was first depicted in The Essential Atlas, a 2009 reference book authored by Jason Fry and Daniel Wallace.
- The Essential Atlas
- Book of Sith: Secrets from the Dark Side
- Star Wars: Force and Destiny Core Rulebook