That's a very weak argument. Eg., the Catalan language is more closely related to French than Spanish (https://en.wikipedia.org/wiki/Gallo-Romance_languages). But the Catalans are certainly "native" to Spain, in that they've lived within the current Spanish borders since before Spain existed. And obviously, someone not being "native" to an area doesn't justify killing or terrorizing them.
Clearly you haven't lived in close proximity to these people.
They trickle in, respect no boundaries and no laws.
Now if they integrated and contributed to the regions culture and economy, that would go a long way towards their acceptance. But that's against the tenents of their religion/culture/ideology and it's demonstrated by their violence.
I'd quote Karl Popper on tolerating the intolerant, but it would be another "weak argument."
You can't drag people who insist on living by pre-medieval norms into the 21st century.
