Hijrah, also spelled Hejira or Hijra (“Flight” or “Emigration”), Latin Hegira, the Prophet Muhammad’s migration (622 ce) from Mecca to Medina in order to escape persecution. The date represents the starting point of the Muslim era. Muhammad himself dated his correspondence, treaties, and proclamations after other events of his life. It was ʿUmar I, the second caliph, who in the year 639 ce introduced the Hijrah era (now distinguished by the initials ah, for Latin anno Hegirae, “in the year of the Hijrah”). ʿUmar started the first year ah with the first day of the lunar month of Muḥarram, which corresponds to July 16, 622, on the Julian calendar. In 1677–78 (ah 1088) the Ottoman government, still keeping the Hijrah era, began to use the solar (Julian) year, eventually creating two different Hijrah era dates, resulting from the differences between a solar and a lunar year.
The term hijrah has also been applied to the emigrations of the faithful to Ethiopia and of Muhammad’s followers to Medina before the capture of Mecca. Muslims who later quitted lands under Christian rule were also called muhājirūn (“emigrants”). The Khawārij (Kharijites), those Muslims who withdrew their support from the arbitration talks that called into question the right of the fourth caliph, ʿAlī, to the caliphate in 657 ce, used the term to describe those who joined them.
The most-honoured muhājirūn, considered among those known as the Companions of the Prophet, are those who emigrated with Muhammad to Medina. Muhammad praised them highly for having forsaken their native city and following him and promised that God would favour them. They remained a separate and greatly esteemed group in the Muslim community, both in Mecca and in Medina, and assumed leadership of the Muslim state, through the caliphate, after Muhammad’s death.
As a result of the Hijrah, another distinct body of Muslims came into being, the anṣār (“helpers”); they were Medinese who aided Muhammad and the muhājirūn. The anṣār were members of the two major Medinese tribes, the feuding al-Khazraj and al-Aws, whom Muhammad had been asked to reconcile when he was still a rising figure in Mecca. They came to be his devoted supporters, constituting three-fourths of the Muslim army at the Battle of Badr (624 ce). When no one of their number was chosen to the caliphate to succeed Muhammad, they declined in influence as a group and eventually merged with other Muslims who had settled in Medina.