Hijrah, (Arabic: “Migration” or “Emigration”) also spelled Hejira or Hijra, Latin Hegira, the Prophet Muhammad’s migration (622 CE) from Mecca to Yathrib (Medina) upon invitation in order to escape persecution. After arriving, Muhammad negotiated the Constitution of Medina with the local clans, thereby establishing the Muslim community as a sociopolitical entity for the first time.
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 Abyssinia (later known as Ethiopia) and of Muhammad’s followers to Medina before the capture of Mecca in 630. Muslims who later left 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. They are praised in the Qurʾān for their early conversion to Islam (sābiqah) and for the subsequent hardships they endured in Mecca, which forced them to migrate to Medina. The Qurʾān describes the muhājirūn as being of a higher status before God (9:20) and states,