Baghdad and the Islamic Golden Age
At its founding, the Abbasid capital of Baghdad became the largest, richest city on Earth outside China and the heart of a golden age of learning. In its House of Wisdom, scholars translated the philosophy and science of Greece, Persia, and India into Arabic — preserving knowledge the West had lost — and pushed it further, giving the world much of the substance of algebra. While early-medieval Europe is remembered as dark, the Islamic world was carrying and brightening the lamp of learning.
A new way to record or transmit information lowers the cost of copying ideas and reorders who holds knowledge and power.