Hegira or Hejira (both: hĭjĪˈrə, hĕjˈərə) [key] [Ar., = Hijra = breaking off of relations], the departure of the prophet Muhammad from Mecca in Sept., 622. Muhammad was a monotheist and preached against the polytheism of the Meccan religion. This aroused the hostility of the merchant leaders of his native city, who derived much of their wealth from pilgrimages to Mecca and its surrounding cities. Forced to flee from his enemies, Muhammad went to Yathrib (later renamed Medina), where he became ruler. The Muslim era is dated from the first day (July 16, 622, in the Western calendar) of the lunar year in which the Hegira took place, and the abbreviation A.H. is used with that year (A.H. 1) and subsequent years.