Permanent Alliance Territory

I currently have a permanent alliance with one of the natives in one of my games. Anyways, their territory and mine is overlapping and Im losing some land I should own. I am not entirely sure how this works. Can I get the land back?

Yea allying with the natives is not necessarily a good thing.
I think allied natives get full control over the land they have influence over. The only thing I know that could be done when the problem is server is to manipulate an European enemy to raze the given settlement. I might be wrong but probably not.