Hans J. Nissen and Peter Heine begin by explaining how ancient Mesopotamian inventions—including urban society, a system of writing, and mathematical texts that anticipated Pythagoras—profoundly influenced the course of human history. These towering innovations, they go on to reveal, have sometimes obscured the major role Mesopotamia continued to play on the world stage. Alexander the Great, for example, was fascinated by Babylon and eventually died there. Seventh-century Muslim armies made the region one of their first conquests outside the Arabian peninsula. And the Arab caliphs who ruled for centuries after the invasion built the magnificent city of Baghdad, attracting legions of artists and scientists.