Leadership after prophet

Leadership of the Muslims after Prophet Muhammad (peace be upon him and his family)
The Qur'an emphasizes the role and significance of leadership in Islam. Allah states: "And remember the day on which we will call together all human beings with their leaders (imams)." (17:71) Therefore, Prophet Muhammad (peace be upon him and his family) was very keen on appointing a successor after himself by the command of his Lord. Allah commands the Prophet (peace be upon him and his family): "O Prophet! Proclaim what has been revealed to you from your Lord [the succession of Imam 'Ali], for if you do not, you will not have conveyed His message, and Allah will protect you from the people." (5:67) This event has been remembered as the event of Ghadir Khum, which was the name of a place intersecting Makkah and Madina, and occurred when the Prophet (peace be upon him and his family)was concluding his hajj rites and heading back with 110,000 companions. When he received the command of Allah, he immediately appointed Imam 'Ali (peace be upon him) as his successor after his death. In approval, the Qur'an says: "This day, I have perfected your religion for you, completed my favor on you, and have chosen for you Islam as your religion." (5:3) All the companions of the Prophet (peace be upon him and his family) paid allegiance to Imam 'Ali (peace be upon him) and accepted him as the first caliph after the Holy Prophet (peace be upon him and his family).
However, only 70 days after this monumental incident, the Prophet Muhammad (peace be upon him and his family) left this life, and the first setback to his teachings occurred when the Muslims did not honor their allegiance to Allah to accept Imam 'Ali (peace be upon him) as the first caliph. Confusion and disarray overtook the Muslims regarding who should succeed the Prophet (peace be upon him and his family) as leader of the Muslim community. In a hasty meeting at Saqifa Bani Sa'ida in Madina, Abu Bakr assumed leadership (632-634), followed by 'Umar ibn al-Khattab (634-644), 'Uthman ibn 'Affan (644-656), and finally 'Ali ibn Abi Talib (656-661).
After the khilafa of 'Ali (peace be upon him), two dynasties followed -- the Umayyids and the Abbasids -- before massive political changes overtook the Islamic world.