Yes, that's exactly what Quigley claims. We sometimes forget that the Iberian Peninsula was invaded by Muslims in the early 700s, and that the last vestiges of Islamic domination were not expelled from Spain until the late 1400s. 700 years of cultural domination will leave a lasting impression on the conquered culture. When and if a subject culture ever re-emerges, it will not be the same; it will have taken on some aspects of the subjugating culture.
Thank you very much!