<human>:  When did the split occur between Shia and Sunni islam?
<bot>: The split occurred in 632 AD. The split was caused by the death of the prophet Muhammad. The Shia islam believes that Ali ibn Abi Talib, Muhammad’s cousin and son-in-law, should have been the next prophet after Muhammad. The Sunni islam, however, does not believe that Ali should have been the next prophet. Instead, they believe that the prophet Muhammad should have had a successor.