Hey i had to do some research for this one but i hope it helps
After the death of Muhammad, the Muslim community could only be in worry to find a quick solution. After some discussion, they decided to split the Muslim world into the two branches; Sunni and Shiite. These two communities started to grow on differences. The group Sunni, believed all succession went to the prophets dear associate, Abu Bakr. On the other hand, you have the Shiite branch, who believe Ali. Ali was the prophets son-in-law, or known as Muhammad’s trust heir.
Hope that got you somewhere, not so strong in the topic, but i hope that’s a starter. good luck!