The annual multiday Islamic pilgrimage known as the hajj began Aug. 31. Each year, a few million Muslims from across the globe flock to Islam’s two holiest mosques, in Mecca and Medina, to perform their religious obligation. But the hajj is more than a religious pilgrimage; it’s an expression of Saudi power. Stewardship over the sacred mosques in Mecca and Medina, and thus the control of the hajj, gives the monarchy in Riyadh a legitimacy no other country that claims to be a leader of the Islamic world has, especially among Sunni Arabs.