Yazdgerd III would have a narrow escape at Marv when Umar's lieutenant was to capture him after Battle of Oxus river, he would save his life only by fleeing to China, far enough from reach of Umar, thus effectively ending the 400-year-old Sassanid dynasty.[4] In 642, Umar launched multi-prong expeditions into Persia, first capturing Isfahan province thus cutting off the northern province of Azerbaijan and southern province of Fars from main empire. in the second phase capturing Azerbaijan and fars thus isolating Yazdegerd III's stronghold Khurasan. The third phase further isolated Khurasan by capturing Kirman, Sistan and Makran in south while Persian Armenia in north.