Expansion New Zealmark for expansion

[Soyabarian Empire]

The thing is, what I have in mind is that they're already have been since when new zealmark was colonized. but I could see the conflict arising from there

but I'll answer the questions.
How long have ethnic soyabarians been settling?

Soyabar has been settling roughly between 800-1000 and colonized New Zealmark. But trough consessions to the natives, part of the ethnic soys fell out of the border

-Has their settling been intentional, or are people just migrating? Either or, why are they settling in other places outside of New Zealmark?

Intentional, and they where moving about, refer to question one for last part of that question

-How did enough settlers get into the western territory to give it a strong likelihood of joining outright? wouldnt that require a lot of settlers?

Their families have been living there for hundreds of years, and people reproduce like rabbits so yeah

-Who currently owns the land, and why didnt they try to stop the soyabarians from coming over?

Warlords and local tribes own the land. Part of the western part, mostly along the coast could be seen as soyabar 2.0 and seen as New zealmark was a colony of soyabar it seems logical