Ashura, which in Arabic means "the tenth day," has several important meanings for Muslims. When the Prophet Muhammad settled in Medina, he encountered Jewish tribes who fasted on the tenth (ashr) of the month to commemorate the Exodus of the Israelites from Egypt under the leadership of Moses. Muhammad, feeling a kinship to Moses, instituted a similar fast among Muslims. The commemoration of Ashura also became a major symbol for Iran, a country that is almost entirely Shi'a, during the Islamic Revolution of 1979.