So in 622, you have the famous migration of Muhammad and his followers to Yathrib, which is renamed Medina, and Medina literally means the city. And from then on, it really becomes the base of Muhammad and the early Muslims. And Muhammad, once he's in Medina, he is no longer just a prophet. He isn't just continuing to have his revelations, according to Islamic tradition, but he essentially rules over Medina and governs it. So he's starting to become both a political ruler and a spiritual ruler. Now, the Quraysh in Mecca are still not happy because Muhammad is continuing to preach and he's continuing to get more and more followers. And so you start having, at first, a series of skirmishes between the armies of the Quraysh, or the members of the Quraysh, and some of the early Muslims.