Omar Ibn Al-Khattab

(Omar I). Born 591 or 581, in Mecca; died Nov. 3 or 4, 644, in Medina. Caliph (from 634) and one of Muhammad’s most prominent associates.

Under Omar, Arab forces conquered considerable territory in Asia and Africa. Omar laid the foundations for the Arab state administration of conquered lands. A system was created for the exploitation of the conquered peoples and distribution of state revenue among the conquerors. Military and civilian vicegeren-cies were instituted and a juridical system was established. Other measures included the establishment of a network of armed camps, which gave rise to the cities of Kufa, Basra, and Fustat. Omar introduced the Muslim calendar. He was slain by a Persian slave.