So like, what were the Spectral Dragonians really?

I’ve had this question for a while and even after seeing the episodes I don’t think it was really ever explained fully besides that one mention from Kai remarking how messed up they are and that he hopes this will free their souls When the sets were first revealed I thought Thunderfang will just take control of them again, but then the ninja get the reveal blades and just start seemingly destroying them and there was no Spectral Tyr like in the sets, I would have thought maybe they are his...