Summary
Arabs spread Islam through preaching, conquest, and trade. After Muhammad died, his followers chose a successor called a caliph. This decision divided the Muslim world into the Shiites and the Sunnis.
The Arab Empire reached new heights under the Abbasid dynasty, and Baghdad became wealthy from trade. The Seljuk Turks moved into the empire, however, and they eventually seized Baghdad. Seljuk rulers called sultans ruled the Abbasid dynasty. The Mongols brought an end to the Arab Empire in 1258 after they invaded Baghdad and burned the city to the ground. Other Muslim groups such as the Moguls and Ottomans built Islamic empires in Asia, Africa, and Europe.
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