“ It dates from 622, the year in which Mahomet “fled” from Mecca to Medina to escape the persecution of his kinsmen of the Koreish tribe. The years of this era are distinguished by the initials “A.H.” (anno hegirae) . The Mahommedan year is a lunar one, about 11 days shorter than the Christian; allowance must be made for this in translating Hegira dates into Christian dates; thus A.H. 1321 corresponds roughly to A.D. 1903. The actual date of the “flight” is fixed as 8 Rabia I., i.e. 20th of September 622, by the tradition that Mahomet arrived at Kufa on the Hebrew Day of Atonement. ”