I hadn't considered it being a protectorate of a larger empire, but I do like that idea - a lot, really! It does open up a lot more opportunities for a wider variety of character types. Thank you so much for the suggestion. :)

I'm starting to envision it as sort of like the relationship the Roman Empire had with its client-kingdoms back in the day. Ooh, and further on in the game, we could open it up to travel to other client-kingdoms on the request of the larger empire they're a protectorate of...

Or if characters wanted to stage an uprising for independence that could totally be a thing they do too...

There are a ton of really interesting possibilities that this presents!