THE GREAT CONQUESTS 35633–34 Three Arab columns march on Syria.
634 Damascus is occupied and lost.
634 Muthanna commands on the Persian front.
635 Abu Bekr dies and is succeeded by Umar.
636 Battle of Buwaib, Muthanna defeats main Persian army.
636 Battle of Yarmouk; Byzantines lose Syria, Palestine, and Leb-
anon to the Arab armies led by Khalid.
637 Battle of Qadasiya; Saad defeats King Yezdegird and Rustem,
the last serious defense of the Persian Empire.
639–42 Conquest of Egypt