EGIRA. — From the Arabic hişrah, “emigration.” It designates the emigration of the Prophet Muḥammad (v.) from Mecca to Medina; with it the Muslim era begins.
The precise day of the Prophet’s emigration, according to the most widespread opinion, would be the 8th of Rabīʿ al-Awwal (i.e., 20 September 622); according to other Muslim sources, the day would be the 2nd or the 12th of the same month. It was the Caliph ʿUmar, the first organizer of the new Muslim state, who established the introduction of the new era for dating, reportedly because he was reproached for sending letters without dates. The use of this dating was introduced, according to the most widespread tradition, in the year 17 of the Hijrah.
Previously, the Arabs gave each year a special name (e.g., “the year of the earthquake,” etc.) or counted the years from some extraordinary or important event. It should be noted that, in fact, the new era (based on a purely lunar calendar) does not begin with the actual emigration, that is, with the 8th of Rabīʿ al-Awwal of the year 1 A.H., but rather with the 1st of Muḥarram (the first month of the Muslim year) of the same year.