Tomorrow night is my Spanish Linguistics class. The prof is from Leon and has a Masters in Performance Guitar from a conservatory in Spain prior to his PhD in Linguistics from UCLA. I'll ask him, but I'm afraid if he has any sources they will all be in Spanish. All of my links on Spanish history and culture are likewise in Spanish. BTW, don't rule out Portugal and Fado as an interesting style. However, all the resources that I am aware of for Fado and other Portuguese music are in Portuguese and you probably don't speak / read that either.
I am somewhat of a Spanish history buff from the Carthagenian period up to about 1600, then I lose interest. I can tell you that when the Carthagenians and Romans arrived most of the tribes in central and southern Spain were Celtic. IIRC, it took about 20 or 30 years for the Romans to eliminate the Carthagenians, but about 200 years to finally conquer the Celts and neither they nor anyone else has ever been successful with the Basques. (Old Basque saying:"When God wanted to create human beings, he started with bones from a Basque cemetary.") It was Basques who destroyed Charlamagne's rear guard, not the Moors as indicated in the Song of Roland. You don't want to piss off the Basques. The mixture of Roman and Celtic people formed a cultural core for the Empire with several important Emperors, writers and teachers being born and educated in Iberia. The people melded with the Romans very well and there were no significant non-Roman areas of cultural resistance other than the previously mentioned Basques.
In any case the Vandals, Suevi (same tribe as those in Swabia in Central Germany today) arrived around 450AD +/- and what was left of the Roman Empire recruited the Visigoths to kick them out. The Vandals left for North Africa and the Suevi retreated to what is now Galicia in the northwest corner of the penninsula. The Visigoths,being true Germans, tried to maintain racial purity, but very slowly mixed with the Hispano-Romanic people until 711AD when, in a fit of pique, one of the disappointed aspirants to the Visigothic throne (don Julian) invited North Africans (Moors), who had recently been converted to Islam, to cross the straits of Gibraltar and fight for him. The Moors defeated the Visigoths led by King don Rodrigo at the Battle of Guadalete and overran the penninsula for themselves. The reconquest by the Christians took 800 years and that was the crucible in which the modern Spanish nation and character were formed.
Notice that the Celts disappeared as a culture about 2,000 years ago. Other than the cultural remnant of a few bagpipes in some northern parts of Spain, nothing remains that I know of. Basically the Moors hammered the various Christian rebels so hard against the Atlantic and Bay of Biscay that their Goth / Hispano Roman curltural differences pretty much disappeared.
I think the really interesting cultural influences for Spain are the interplay of Islamic Moors, Christian Goth / Hispano-Romans and Jews between 711 and 1492. For instance the Caliph of Cordoba Al Hakam II, who indisputably had the most culturally significant kingdom west of China between 500AD and 1500AD, had red hair and blue eyes. Does that suggest a little "race-mixing" among these competing cultures? In any case, if I were looking at the roots music of Spain I would chose Muslim and Jewish influence in modern music. The earliest remnants of "Spanish" poetry are some fragments of love songs called "Jarchas" which are from the Moorish occupied areas and appear to be Jewish in origin, written in Arabic script and the language is an early Latin/Spanish variant known as "Romance".
My second choice would be gypsy influence and I would spend some time looking at gypsy influence on Federico Garcia Lorca, the early 20th Century Andalusian poet/playwright and his collegues. There might be some remnant of Celtic musical culture, but I suspect it will be very difficult to get sources.
That is probably more than you wanted to know, but maybe some of that will provide you with some ideas or leads that will be useful.
thanks for the suggestion though.
