Some argue the Muslim world never recovered intellectually after the sack of Baghdad. That part of the world became an intellectual backwater.
Intellectually, yeah, good one. The muzzie golden age is exaggerated, to say the least.
Their earliest experience of a large quantity of classical learning was their incineration of the Great Library of Alexandria.
Later muzzies encountered a storehouse of classical selections that had been carted off to a 'heretical' monastery in pre-muzzie Iran. Which luckily was found by someone with some intellectual curiousity. Today he'd be beheaded while the crowd of his former soldiers chanted "allah akbar".
The Turks acquired some of the stuff preserved by the Byzantines, but were already familiar with it from their own ingress to the Middle East.
The Spanish Reconquest of Spain led to rediscovery/reintroduction of lost classical texts (in Arab translations, mostly) left behind by the Saracens as they were slowly expelled. That Spanish cache was arguably the most valuable literary collection in history. :^)