[Rebelbase]

I had to look it up:

suzerainty [ˈsuːzərəntɪ] n pl -ties
1. (Government, Politics & Diplomacy) the position, power, or dignity of a suzerain
2. (Government, Politics & Diplomacy) the relationship between suzerain and subject

su·ze·rain (szr-n, -z-rn)
n.
1. A nation that controls another nation in international affairs but allows it domestic sovereignty.
2. A feudal lord to whom fealty was due.

[Lorica]

Thanks. I would have had to look up the definition if you hadn’t already posted it!

[Ernest_at_the_Beach]

This will do:

A feudal lord to whom fealty was due.