The Rashidun Caliphate (Arabic: اَلْخِلَافَةُ ٱلرَّاشِدَةُ al-Khilāfa-al-Rāshidah) (632–661) was the first of the four major caliphates established after the death of the Islamic Prophet Muhammad. It was ruled by the first four successive caliphs (successors) of Muhammad after his death in 632 CE (AH 11). These caliphs are collectively known in Sunni Islam as the Rashidun, or "Rightly Guided" caliphs (اَلْخُلَفَاءُ ٱلرَّاشِدُونَ al-Khulafā’ur-Rāshidūn). This term is not used in Shia Islam as Shia Muslims do not consider the rule of the first three caliphs as legitimate.
The Rashidun Caliphate is characterized by a twenty-five year period of rapid military expansion, followed by a five-year period of internal strife. The Rashidun Army at its peak numbered more than 100,000 men. By the 650s, the caliphate in addition to the Arabian Peninsula had subjugated the Levant, to the Transcaucasus in the north; North Africa from Egypt to present-day Tunisia in the west; and the Iranian plateau to parts of Central Asia and South Asia in the east.
The caliphate arose out of the death of Muhammad in 632 CE and the subsequent debate over the succession to his leadership. Abu Bakr, a close companion of Muhammad from the Banu Taym clan, was elected the first Rashidun leader and began the conquest of the Arabian Peninsula. He ruled from 632 to his death in 634. Abu Bakr was succeeded by Umar, his appointed successor from the Banu Adi clan, who began the conquest of Persia from 642 to 651, leading to the defeat of the Sassanid Empire. Umar was assassinated in 644 and was succeeded by Uthman, who was elected by a six-person committee arranged by Umar. Under Uthman began the conquest of Armenia, Fars and Khorasan. Uthman was assassinated in 656 and succeeded by Ali, who presided over the civil war known as the First Fitna (656–661). The war was primarily between those who supported Uthman's cousin and governor of the Levant Muawiyah, and those who supported the caliph Ali. The civil war permanently consolidated the divide between Sunni and Shia Muslims, with Shia Muslims believing Ali to be the first rightful caliph and Imam after Muhammad. A third faction in the war supported the governor of Egypt Amr ibn al-As. The war was decided in favour of the faction of Muawiyah, who established the Umayyad Caliphate in 661.