Battle of Nahavand
The Battle of Nahavand ( ', '), also spelled Nihavand or Nahawand, was fought in 642 between Arab Muslims under Umar and Sassanid armies. The battle is known to Muslims as the "Victory of Victories." The Sassanid King Yazdegerd III escaped to the Merv area, but was unable to raise another substantial army. It was a victory for the Rashidun Caliphate and the Persians consequently lost the surrounding cities including Spahan (renamed Isfahan).