Islam did have an amusing couple of centuries, the 12th and 13th. However, the learning of Islam derived not from within, but from those bastions of the Christian Byzantine Empire the Muslims overran.
It is there that they took over the remnants and trappings of Classical Civilization, which they had handily destroyed. Northern Africa, Egypt, Lebanon, Syria, Constantinople ... those were all Christian lands, which over the centuries were forcibly converted to Islam by the sword.
The proof of the matter is that since those heady times of supposed Islamic intellectual glory, the Muslim lands have actually retrogressed. Their civilization, such as it is, is stagnant: has been for nigh on a 1,000 years.