Victorian twaddle. There were no "Dark Ages", and "Spain" (which didn't exist in 720 AD) was no more advanced than any number of other European kingdoms. Charles Martel was grandfather to Charlemagne, who united Western Europe and was crowned Emperor 80 years later. The "dark ages" are nothing more than an invention of Victorian historians romanticizing about the fall of Rome.
Spain, to say the least, has been around a very long time ~ Trajan, the Roman Emperor, was a Spaniard.
Now, what was it you were saying about "The Dark Ages"? I'd suggest you go find out how many books were published in Western Europe from 538 AD to about 1066 AD ~ get back to us when you find some eh!