It's a long topic, but if I were you I'd start with "The Reconquista" and go from there. Spain was conquered by Iraq once upon a time (see Ummayad dynasty) and later on by North Africa. Cornishmen under the leadership of San Cho Noe I (Sancho I) arrived in the nick of time to found three kingdoms ~ Castile, Carvajal, and Leon ~ to start up the Reconquista and take Spain back from the Arabs and North Africans.
In the end most of the invading populations converted to Christianity (rather than be shipped out or killed), and Columbus discovered America. Guess where they moved?
Oh, yes, El Cid made love to Sophia Loren and all was cool.