The Basque were the 'original' settlers. They were already there when everyone else arrived.
"The basic problem of the moriscos was a problem of integration. The moriscos remained a class apart, with their own language and religion and a way of life directed by Islamic law. In Aragon and Valencia, descendants of those who had submitted to forced conversion, they were a geniune enclave of Islam within Spainm resistant to christianisation and hispanisation, with their own leaders and upper class, their rich and their poor, all equally immune to integration. And as their spiritual home was outside Spain so, it was suspected, was their political allegiance.....
"Muslim Spain was south-eastern Spain. It was here that the real danger was seen to lie. The rapid growth of moriscos of Valencia and Aragon threatened to soon...tip the balance in favor of Islam.
"...on 9 April 1609 it was decided to expel the moriscos from the whole of Spain, beining with Valencia. It was here, as has been seen, that the problem of the moriscos was considered most acute, because of their numbers, their concentration in mountain fastness, their situtation near a coast-line easily accessible from North Africa. It was logical to expel them first, before they organized...or called in outside help...
"...While the diligence and efficiency of the moriscos are not in doubt, it is a myth that they were the only productive classes in Spain; most of the trades and occupations in which they (moriscos) specialized, including irrigation, were also widely practiced by Sparniards....If we are to judge by wage and price levels in those sectors of the economy where the moriscos had been most productive, the expulsion had little material consequences..."
This is an answer which will need to be discussed in the future.