It is known that the Prophet Muhammad was born on a Monday in the month Rabi al-awwal. Many people consider the 12th to be the Prophet’s birthday, but according to Islamic sources it is more likely that he was born on Monday the 9th day of Rabi al-awwal. But the 12th day of that month is known as the day when the Prophet Muhammad arrived in Medina and as the day of his death. Marking the Prophet’s birthday on the 12th was introduced in Egypt during the Fatimid Caliphate in the Middle Ages, and is still celebrated on that day in some Muslim countries and by some Muslims.