It had someone living there, those someone's weren't asked and their land handed over to someone else. If we see it from the perspective of it having being a British colonial project, then it's even worse having gone from one colonial master to another without asking the natives.
> of an inhabited nation
https://www.britannica.com/dictionary/nation
> a tribe of Native Americans or a group of Native American tribes that share the same history, traditions, or language
They're not native americans.
> a large area of land that is controlled by its _own_ government
Mandatory Palestine was controlled by British.
So it was not an inhabited nation, I guess.