The Iberian Peninsula was a major melting pot with peoples arriving from all over Europe, the Med, Middle East, and North Africa.
Genetic history of the Iberian Peninsula
DNA study shows 20 percent of Iberian population has Jewish ancestry, by Nicholas Wade, December 4, 2008. Spain and Portugal have a history of fervent Catholicism, but almost a third of the population now turns out to have a non-Christian genetic heritage. About 20 percent of the current population of the Iberian Peninsula has Sephardic Jewish ancestry, and 11 percent bear Moorish DNA signatures, a team of geneticists reports.
Not surprisingly, there is a strong flow in the other direction and a lot of Andalusian blood in Morocco.
From what I gather, there were lots of Moop soldiers but they had spread so far, so fast and still had so many border clashes that they relied heavily on converts for day to day administration and they weren't that rigid on making sure everyone was a perfect muslim. So it makes sense that it could be such a melting pot in spite of being dominated by the very militant muslims of the day. And the same thing happened after a fashion when the Christians won it all back. They didn't tolerate other relgions so you had to convert or go but they let the moopish influence in the art and architecture remain in force but with some christian influences, a style called mudejar architecture.
The presence of Jews in Southern spain prior to the re-conquista by the christians lasted a long timeindeed. This was when the Muslims didn't want to murder all jews. So they lived, worked, thrived under Moopish rule.
As an example, the synagogue in Cordoba was built in 1319 and remained in use until 1492 when all the jews were booted from Spain (or forced to covert). It's still there, having been used for different things over the years which is why it still survives. You can see that arabian style but with stars of david and hebrew writing worked into the decorative flourishes. It's not very big, as I recall but it's been 20 years and I was only there once. The Santa Cruz district in Seville was the jewish quarter, or juderia, during the moorish period but again the jews were all expelled and it became what is today one of the most picturesque areas of Seville. 