There are three questions in the story of Islamic history. What happened? How do we know this? Why does it matter? The Introduction takes a brief look at the geography of Islam now and in the past to show how these questions may be answered. Is Islamic history the history of those places where Muslims have been in power? Or is it the history of Muslims wherever they may be? Islam nowadays is everywhere. Until the modern period, it was much easier to define where Islam was. Why didn't the Arabs just stay put in Arabia? What motivated them to move?