Hejira or Hejra (Arabic, “going away”), a word applied to Mahomet's flight from Mecca to Medina in A.D. 622; Calif Omar, 17 years later, adopted this date as the starting-point of a new Mohammedan calendar.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Hejaz, El * Hel