Why were the 1000s and 1100s golden age for al-Andalus?

Answer 1

It was a golden age for al-Andalus because the scholars made important contributions to the study of mathematics, Astronomy, geography, medicine and philosophy. Also because the Jews had freedom there and they contributed important stuff too.

Answer 2

If your question is asking why Spain's Golden Age was under Muslim control as opposed to some other period in its history, this is not the case. The 1500s and the period of Spanish conquest in the New World brought unprecedented wealth to Spain and promoted a flourishing of the Spanish Hapsburg Dynasty. This lead to territorial expansion and much wealth until the Thirty Years War in 1618-1648. The Golden Age of Spain under Islamic control was very different than the Hapsburg Golden Age, but it is not the only Golden Age of Spain.

If your question is asking why the Muslim period was a Golden Age in Spain, it was due to the Umayyad Caliph's open-minded policy of toleration. Abd-el Rahman I al-Umayya barely arrived in Al-Andalus (Islamic Spain) with his life and to avoid insurrection, he founded a very liberal set of codes for the time period. As Iberia was predominantly Catholic and non-Arab, made up of Europeans and Amazigh (West North African Berbers), these codes functioned to benefit these peoples. The tolerant conditions in Spain allowed Jews and Christians to observe their faith without intrusion provided they pay certain extra taxes and not offend Muslim sensibilities. Under these liberal (for the time) permissions, Jews, Christians, and Muslims read each others' literary works and discussed them in open forums. Jews copied Islamic poetry and Muslims enhanced their understanding of Jewish jurisprudence. All three faiths interpreted the works of the Ancient Greeks and translated Arabic documents into Latin for European consumption. This 400 year liberal atmosphere 750-1150 allowed for a flowering of culture which was unique for the times.