The Quran teaches that Muslims have an obligation to fight in order to spread their faith to new lands, and in order to gain new converts. The word ‘fight’ does not always refer to battle, but can also refer to the labors of missionary work. A ‘fight’ for religious expansion is known in Islam as a Jihad.
Guided by the principal of Jihad, the armies of Islam were united. They fought with courage and strength against their enemies, and continued to expand their borders and influence. By 650 A.D., their conquests had led them to possess much of the lands around the Mediterranean Sea, including Egypt, Persia, Iraq, Iran, and surrounding regions.