So in less than 200 years, Islam went from not existing to being the religious and political organizing principle of one of the largest empires in the world. And that story begins in the 7th century CE, when the angel Gabriel appeared to Muhammad, a 40-ish guy who made his living as a caravan trader, and told him to begin reciting the word of God. Initially, this freaked Muhammad out, as, you know, it would, but then his wife and a couple other people encouraged him, and slowly he came to accept the mantle of prophet. A few things to know about the world Islam entered. First, Muhammad's society was intensely tribal. He was a member of the Quraysh tribe, living in Mecca, and tribal ties were extremely important. Also at the time, the Arabian Peninsula was like this crazy religious melting pot.