Over two million Muslims begin the haj in Saudi Arabia this week, amid fears of sectarian violence and militant attacks, as well as the stampedes that have marred the pilgrimage in recent years. Thousands of people began arriving in the holy city of Mecca, with crowds gathering outside the Al Haram mosque for prayer. With up to three million people expected to attend the haj this year, many pilgrims desperately need assistance to take part in the five-day ritual, set to begin on Friday (December 29). Elderly men and women are escorted by younger pilgrims to converge on the Grand Mosque in Mecca and follow the route around the rocky mountains of the ancient city, according to a tradition established by the Prophet Mohammed. "This man was able to come here from (Egypt). He is 86 years old. Of course, he took part in the umra on this wheelchair. On Thursday we will go to Arafat Mountain and we will sleep there because Mina is crowded. He will do the pilgrimage, inshallah," said a pilgrim. But huge crowds and religious fervour set the stage for frequent disasters in the haj, and despite advice by authorities to avoid deadly over-crowding, many pilgrims insist on following a rigid timetable for the ritual.