The document summarizes the rise of the Islamic Caliphate following the death of Muhammad and the subsequent split between Sunni and Shia Islam. It describes the expansion of the Caliphate under the first four successors or "Caliphs" of Muhammad, known as the Rashidun Caliphate. It then discusses the Battle of Siffin in 657 AD and the assassination of Ali, which led to the division between Sunnis, who believed in elected Caliphs, and Shias, who revere Ali and his descendants. The document focuses on the importance of the Battle of Karbala in 680 AD for the Shia tradition.