"The era of the so-called righteously guided caliphs [Three of whom were offed.]didn’t last long, [Nor did they.]but it was superseded by any number of other Islamic “golden ages,” which flourished for far longer. The Abbasid caliphate, with Baghdad as its bustling center, was one of the most successful empires the world had ever seen. From the eighth to 13th centuries, the empire prospered, with unprecedented advancements in science, medicine, and philosophy. Students from Europe flocked to Muslim universities, hoping to study with the world’s greatest doctors, thinkers, and theologians. Muslims today, particularly in the Arab world, enter into tortured debates over what went wrong, with this history as subtext."