There are numerous competing ideas about Sharia, just as there are within any legal tradition. So people who embraced this worldview were called Muslims because they submitted to the will of God and they became part of the Ummah, or community of believers. This would be a good moment for an Uma Thurman joke, but sadly, she is no longer famous. I'm sorry if you're watching this, Uma Thurman. Being part of the Ummah trumped all other ties, including tribal ties, which got Muhammad into some trouble and brings us, at last, back to history. So as Muhammad's following in Mecca grew, the Ummah aroused the suspicion of the most powerful tribe in Mecca, the Quraysh. And it didn't matter that Muhammad himself was born into the Quraysh tribe because he wouldn't shut up about how there was only one god, which was really bad news to the Quraysh tribe because they managed the pilgrimage trade in Mecca, and if all those gods were false, it would be a disaster economically.