Thestrals, known colloquially as 'Bat Ponies', have deep roots in Equestria. However, before they became fully integrated into our own society, they dwelled in a mysterious land, not known to normal ponies, known as Nocturna. Though it's history is brief, and often tumultuous, knowing the history of this lost land it is nonetheless vital to understanding our current state of affairs.
Before Reading, I ask that you first go back to Legacy and Nocturna Eternal. These are essential to understanding where this history ultimately leads.