Hijrah

  The beginning of revelation to the Prophet Muhammad and the proselytizing of absolute monotheism marked the Mecca period. When the persecution of Muslims and the Prophet became intolerable, they decided to emigrate to Yathrib (later known as Medina), about two hundred miles north of Mecca. Islamic history calls this event Hijra. It occurred in 622 CE and is the basis of Islamic chronology. Muslims date their history not from the Prophet's birth nor from his reception of the first revelati