If you want to complete 100% or any% do you need to make your own kingdom?

to conquer all the factions does that mean you need to make your own kingdom and beat everyone else or can you jut ride with 1 faction and attack all the others?

same with any%, do you need to make your own kingdom to conquer another faction? i know in game you don't but to complete the run i thought u might need to.

hopefully not in these because i prefer to stay with a faction and conquer all the others :)