Answer:
While alive, Mohammed created a political empire. After his death, the community was left without a leader. Since Mohammed hadn't named the next leader before his death, panic spread across the empire. Some clans abandoned Islam altogether, other refused to pay taxes, and some even declared themselves prophets. The next four people to lead the empire all knew Mohammed and became known as the "rightly guided" caliphs. Each one of the caliphs played a part in expanding the Muslim empire to 4X its size. The Muslims succeeded because they were energized by their faith, and let Christians and Jewish people keep theirs. Over time many cultures in the Muslim empire converted to Islam because of Islam's message of equality.
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