Explanation: During the early Islamic expansions, much of the Iberian peninsula was taken over by Muslim polities - almost all, in fact, except for a little strip of land up north populated by mountainfolk.
I'm sure it'll be fine if we just leave them, it's really not worth the blood and treasure to occupy the bastards. It's not like a couple of hillbillies could reverse the entire course of history of the Iberian peninsula by sheer stubbornness and a generous application of religiously motivated violence by sustained action over the course of some 600 years.
... right...?