It's possible you're thinking of a specific story or legend that is not widely known. To help me identify what you're looking for, could you please provide more context?
For example:
* Where did you encounter this idea? Was it in a book, a movie, a game, or somewhere else?
* What else do you know about the thrones? Were they in a specific location? Were they associated with any particular characters or figures?
With more information, I might be able to help you find the source of this idea.