Board Thread:Lore Discussion/@comment-24.113.168.122-20130520103810/@comment-9156240-20130529235404

There are also Dragon Priests on Solstheim and I don't think that the island is divided into holds. So whatever significance the masks have, I doubt it has something to do with the holds.

Also, the Dragon Priests were around before Skyrim was divided into 9 holds, although I think someone has already said this.