
Christians believe Jesus is a man who preached and performed miracles and died on the cross but was resurrected. But for historians, the crucifixion is the least unreliable indicator of the Jesus' existence.
Muhammed’s first year in Medina, in year 622 of the Christian era, marks the beginning of the Muslim era and the birth of a new religion, civilisation, empire and calendar. The Hegira, Muhammed’s visit to the Mecca in Medina, also marks a major change : from then on, believers will pray in the direction of this new sacred place and no longer in the direction of Jerusalem.