Averroes

Scholars have written about this and explained the reasons behind it. When Muslims grew more powerful than their rivals and were living through what is often called their Golden Age, they gradually became complacent, lost sight of Allah, and indulged excessively in philosophy, music, dance, and other worldly pursuits. Infighting began to intensify, internal divisions widened, and the authority of the Caliph steadily weakened, largely due to their own shortcomings. Then Allah ﷻ sent a calamity upon the Muslim world in the form of the Mongols and Tatars. And when Muslims proved unable to stop them, Allah ﷻ Himself brought an end to their devastation by opening their hearts to Islam and guiding them towards embracing it. In the centuries that followed, Muslims once again established powerful empires across the world, many of which ruled for centuries. But as they fell into similar habits of complacency and moral decline, another calamity befell them in the form of European colonialism, the consequences of which continue to be felt to this day. For this same reason Allamah Iqbal said: “Hai Ayan Yorish-e-Tatār Ke Afsane Se Pasban Mil Gaye Kaabe Ko Sanam Khane Se.” (It is evident from the story of the Tatar conquerers, Kabah finds defenders, even from the temple worshippers.)