The cavern-dwelling Eellayin people formed a civilization on the planet Polis Massa before it was destroyed in a mysterious cataclysm, leaving an asteroid belt behind. The few details about the Eellayin or the disaster that destroyed their homeworld caused them to vanish from most known history.
Circa 519 BBY, long after their homeworld was destroyed, another civilization from the Subterrel sector investigated the remains of Polis Massa. These people, the Kallidahin, became so strongly associated with the archaeological investigation of Polis Massa that they became known as Polis Massans. The Polis Massans' main concern was uncovering what connection they may have had with the ancient Eellayin.
- Star Wars: Revenge of the Sith: The Visual Dictionary (First mentioned)
- Star Wars: Complete Locations (First identified as Eellayin)
- The New Essential Guide to Droids
- The Complete Star Wars Encyclopedia
- The Clone Wars Campaign Guide
- Star Wars: The Official Starships & Vehicles Collection 31
- Strongholds of Resistance