Omar I
 oxford
 views  updated May 23 2018Omar I (
c.581–644), 
Muslim caliph 634–44. Converted to 
Islam in 617, after becoming caliph he conquered 
Syria, 
Palestine, and 
Egypt, in the course of which (
c.641) the library at Alexandria was burnt.
  The Oxford Dictionary of Phrase and Fable ELIZABETH KNOWLES