Umar, who served as caliph for ten years, ended his rule with a significant victory over the Persian Empire. The struggle with the Sassanid realm had opened in 687 at al-Qadisiyah, near Ctesiphon in Iraq, where Muslim cavalry had successfully coped with elephants used by the Persians as a kind of primitive tank. Now with the Battle of Nihavand, called the "Conquest of Conquests," 'Umar sealed the fate of Persia; henceforth it was to be one of the most important provinces in the Muslim Empire.
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Umar (RA)