The Rashidun Caliphate (Arabic: الخلافة الرّاشدة, romanized: al-Khilāfat ar-Rāshidah) was the early Islamic polity led by the first four successive caliphs (lit. "successors"): Abu Bakr, Umar, Uthman, and Ali, collectively known as the Rashidun, or "Rightly Guided" caliphs. These early caliphs led the Muslim community (Ummah) from the death of the Islamic prophet Muhammad in 632 CE to the establishment of the succeeding Umayyad Caliphate in 661 CE, and marked the beginning of the transition out of late antiquity into the Near East's Islamic period.
The title Rashidun stems from the doctrine in Sunni Islam that the caliphs were "rightly guided". Endowed with superior piety and wisdom, their era is regarded in Sunni Islam as a "golden age", second only to the lifetime of Muhammad in sanctity and in providing moral and religious guidance. Sunni Muslims consider the "rightly guided" reign of the first four caliphs as a model to be followed and emulated from a religious point of view. The term Rashidun is not used by Shia Muslims, who make up 10–15% of the global Muslim population, as they only consider Ali to have been a legitimate caliph and reject the first three caliphs as usurpers; while Ibadi Muslims only regard the first two caliphs, Abu Bakr and Umar, as rightly-guided caliphs.
The caliphate's first 25 years were characterized by rapid military expansion during which it became the most powerful economic and military force in West Asia and Northeast Africa. By the 650s, in addition to the Arabian Peninsula, the caliphate had subjugated the Levant and parts of Transcaucasia to the north; North Africa from Egypt to the edge of present-day Tunisia in the west; and regions stretching from the Iranian Plateau to parts of Central and South Asia in the east. The caliphate ended after five years of internal strife.

Following Muhammad's death in June 632, Muslim leaders debated who should succeed him. Unlike later caliphates which were ruled by hereditary dynasties, the Rashidun caliphs were either chosen by a small group of high-ranking companions of Muhammad in shūrā (lit. 'consultation') or appointed by their predecessor. Muhammad's close companion and father-in-law Abu Bakr (r. 632–634), of the Banu Taym, was elected the first caliph in Medina and presided over the conquest of the Arabian Peninsula. The only Rashidun caliph not to die by assassination, he was succeeded by Umar (r. 634–644) of the Banu Adi, who was also a close companion and father-in-law of Muhammad. During Umar's reign, the caliphate expanded at an unprecedented rate, conquering more than two-thirds of the Byzantine Empire and nearly the entire Sasanian Empire.
Following the assassination of Umar, Uthman (r. 644–656) of the Banu Umayya, who was a senior companion and son-in-law of Muhammad, was elected caliph. His reign oversaw the completion of the conquest of Persia in 651 and continued the military campaigns into Byzantine territories. Uthman was assassinated in June 656 and was succeeded by Ali (r. 656–661) of the Banu Hashim, the cousin and son-in-law of Muhammad, who moved the caliphate's capital to Kufa. Ali's accession to the caliphate triggered the First Fitna, a civil war ignited by the refusal of Uthman's kinsman from the Umayyad clan and the long-time governor of the Levant, Mu'awiya ibn Abi Sufyan (r. 661–680) to recognize Ali's suzerainty and pledge allegiance to him until Uthman's killers were brought to justice.
After the Battle of Siffin between Ali's Iraqi army and Mu'awiya's Syrian forces, which resulted in a stalemate and inconclusive arbitration, a faction of Ali's erstwhile supporters, known as the Kharijites, seceded and rebelled against both sides, opposing his decision to arbitrate with Mu'awiya. Following Ali's assassination by a Kharijite dissident in 661, Mu'awiya invaded Iraq with his Syrian army and compelled Ali's eldest son and successor Hasan—who had been chosen as caliph in Kufa—to abdicate in his favour. Mu'awiya then entered Kufa and received the pledge of allegiance from the Iraqis, with his suzerainty being acknowledged throughout the Caliphate, before being proclaimed caliph at a ceremony in Jerusalem, thus founding the Umayyad Caliphate.

Names and definitions
The Arabic word rāshid (راشد) means "one who has attained the right path or maturity". The expression al-Khulafāʾ ar-Rāshidūn (الْخُلَفاءُ الرّاشِدُونَ) is an honorific title meaning "successors or representatives who have been guided to the right path". This also implies that they were endowed with superior piety and wisdom, and that their era was a "golden age" following Muhammad in holiness, moral and religious guidance.
During the eighth and ninth centuries, there was a diversity of opinions about which caliphs were rāshidūn. After the ninth century, however, the first four caliphs became canonical as rāshidun in Sunni Islam. The Umayyad caliph Umar ibn Abd al-Aziz (r. 717–720) was cited as a fifth rāshidun caliph by the Sunni hadith collector Abu Dawud al-Sijistani (d. 889). Another hypothesis may have included Hasan ibn Ali (c. 625–670) as a fifth rāshidun caliph, because his six-month reign was needed to complete a thirty-year period after Abu Bakr's ascension, which was predicted by Muhammad in a Sunni hadith as the length of the prophetic succession.
In Shia Islam, the temporal and spiritual heritage of Muhammad is represented by the Imams, who (except for the first Imam Ali, who was his son-in-law) were his descendants. The first three Rashidun caliphs are regarded in Shia Islam as having usurped the rights of Ali, and the later Umayyad and Abbasid caliphs are regarded as having usurped the rights of the following Imams.

Ibadism does not see the caliphate as an institution that includes all believers and that must be obeyed. It considers the first two caliphs after Muhammad, Abu Bakr and Umar, as being on the right path; and their successors, including Uthman and Ali, as having strayed into injustice.
History
Background
According to the traditional account, Muhammad began receiving what Muslims consider to be divine revelations in 610 CE, calling for submission to the one God, preparation for the imminent Last Judgement, and charity for the poor and needy. As Muhammad's message began to attract followers, he was also met with increasing hostility and persecution from Meccan elites. In 622 CE Muhammad migrated to the city of Yathrib (now known as Medina), where he began to unify the tribes of Arabia under Islam, returning to Mecca to take control in 630 and order the destruction of all pagan idols. By the time Muhammad died c. 11 AH (632 CE), almost all the tribes of the Arabian Peninsula had converted to Islam, but disagreement broke out over who would succeed him as leader of the Muslim community.
Among those seeking to be the successor of Muhammad were:

the Muhajirun, senior companions of Muhammad, including those known as "The ten to whom Paradise was promised" (al-ʿashara al-mubashsharūn).
the Banu Hashim; members of the Hashemite clan including Ali and Abbas ibn Abd al-Muttalib, who were the closest blood relatives to Muhammad;
the Ansar; the people of Medina who had sheltered Muhammad and the early Muslim but were now "fed up" with being dominated by refugees from Mecca.
the members of the aristocratic Quraysh tribe, including the powerful Umayyad clan who held a strong position in Mecca and maintained influential commercial and financial ties.
In determining Muhammad's successor, the strong support and companionship given to him from the early years of his prophethood, praise given by Muhammad and the close kinship ties established with him came to the fore as the determining attitude. The first two caliphs gave their daughters to Muhammad in marriage while the next two married with Muhammad's daughters.
Timeline
(Note that a caliph's succession does not necessarily occur on the first day of the new year.)

Historiography
The histories were written “a posteriori” in the form of “founding conquest stories” based on nostalgia for the golden age in Abbasid times. Humphrey, quoted by Antoine Borrut, explains that the chronicles related to this period were created according to a pact-betrayal-redemption principle. A similar state of uncertainty arises in genealogy (and maybe in other people's tags) as well; modern historians do not accept genealogies from the pre-Islamic and early Islamic periods as verifiable information. Genealogies were oral products of the ayyām (Days of the Arabs) culture, which was established in Bedouin and semi-Bedouin Arab communities, as part of other traditional narrative forms based on lineage boasting. This form of transmission is one in which narratives are transmitted in a flexible manner, reshaped according to the social expectations present in each performance and the interaction between the narrator and the listener.
Early Islamic archaeology offers no evidence of a developed Islamic identity during this period. Unlike prominent historical figures of the period such as Mu'awiya I and Abd Allah ibn al-Zubayr, no archaeological evidence such as coins, seals, rock inscriptions, tombstones, etc., has been found that could indicate a "new Islamic rhetoric" predating Abd al-Malik or a political hegemonic state in the name of the four caliphs. In the collections of Islamic literature, a tradition of "letter writing" can be found under the categories of Maktubat, Risalat, etc. and a large number of letters, which have need to been historically verified, are attributed to notable early Islamic figures including Umar as well as Muhammad and continue to be the subject of various religious-legal studies. Stories and speeches written in the name of Muhammad, Umar, or Ali are compilations dating from centuries after the period in which they are believed to have lived.
However, at least one inscription has been found dating to the period that mentions Umar by name and the date of his death, known as the inscription of Zuhayr. Its three lines read:
In the name of God
I, Zuhayr, wrote (this) at the time Umar died, year four
And twenty
Robert G. Hoyland, finds it "all but certain" that the inscription refers to the historical Umar ibn al-Khattab, adding, "and yet the absence of any epithet or title is striking". Inscriptions may be susceptible to alternative readings due to the erasure of letters by environmental influences and inadequate writing systems, and unless specifically stated, dating can only be done approximately based on the "writing style". Other possible mentions in inscriptions from that era could be read as from Uthman ibn Affan include: an inscription at Tayma, Saudi Arabia, and one at the Alia Palace archaeological site in Makkah Province, Saudi Arabia. According to Tom Holland, Umar's historicity is beyond dispute. An Armenian bishop writing a decade or so after Qadisiyya describes Umar as a "mighty potentate coordinating the advance of the sons of Ismael from the depths of the desert". Undeniable gaps between individuals' historical identity and their narrative-imaginative identity and life stand before historians as indisputable realities. These identities are sometimes supernatural personalities to whom or their representatives (Imams, Qutbs, Sheikhs) are attributed with unseen powers, including special inspirations and detailed knowledge of the future (books of the unseen), extraordinary charisma beyond human limits to the point of arranging the universe for them (the sunset is delayed for Ali’s prayer), and help in great crises ("help me Muhammad, help me Ali").
Abu Bakr's reign (632–634)
Origin and accession to Caliphate
After Muhammad's death in 632 AD (11 AH), a gathering of the Ansar (lit. 'Helpers'), the natives of Medina, took place in the Saqifah (courtyard) of the Banu Sa'ida clan. The general belief at the time was that the purpose of the meeting was for the Ansar to decide on a new leader of the Muslim community among themselves, with the intentional exclusion of the Muhajirun (migrants from Mecca), though this has later become the subject of debate.
Nevertheless, Abu Bakr and Umar, both prominent companions of Muhammad, upon learning of the meeting became concerned about a potential coup and hastened to the gathering. Upon arriving, Abu Bakr addressed the assembled men with a warning that any attempt to elect a leader outside of Muhammad's own tribe, the Quraysh, would likely result in dissension as only they can command the necessary respect among the community. He then took Umar and another companion, Abu Ubayda ibn al-Jarrah, by the hand and offered them to the Ansar as potential choices. He was countered with the suggestion that the Quraysh and the Ansar choose a leader each from among themselves, who would then rule jointly. The group grew heated upon hearing this proposal and began to argue amongst themselves. Umar hastily took Abu Bakr's hand and swore his own allegiance to the latter, an example followed by Abu Ubayda ibn al-Jarrah, the Ansar, the Quraysh tribe and other gathered men. Abu Bakr adopted the title of Khalīfaṫ Rasūl Allāh (خَلِيفةُ رَسُولِ اللهِ, "Successor of the Messenger of God").
Sunni Muslims believe that Abu Bakr was near-universally accepted as head of the Muslim community (under the title of Caliph) as a result of Saqifah, though he did face contention as a result of the rushed nature of the event. Shia Muslims contend that the debate between Muhammad's companions on which of them should succeed him in running the affairs of the Muslims took place in the absence of Muhammad's household, who were busy with his burial.
Several companions, most prominent among them being Ali ibn Abi Talib, initially refused to acknowledge his authority. Ali may have been reasonably expected to assume leadership, being both cousin and son-in-law to Muhammad. The theologian Ibrahim al-Nakha'i stated that Ali also had support among the Ansar for his succession, explained by the genealogical links he shared with them. Whether his candidacy for the succession was raised during Saqifah is unknown, though it is not unlikely. Abu Bakr later sent Umar to gain Ali's allegiance, resulting in an altercation. However, after six months, the group made peace with Abu Bakr and Ali offered him his fealty. In addition, Chamieh argues that the dissension of most of the tribes that had submitted to Islam during the Ridda Wars demonstrated not disbelief but that Abu Bakr did not have a consensus of the Muslim community to be caliph.
Ridda Wars
Troubles emerged soon after Muhammad's death, threatening the unity and stability of the new community and state. Apostasy (in the form of new claimants to prophethood and the refusal of obedience and payment of taxes to Abu Bakr), spread to every tribe in the Arabian Peninsula with the exception of the people in Mecca and Medina, the Banu Thaqif in Taif, and the Banu Abd al-Qays of Oman. In some cases, entire tribes apostatized. Others merely withheld zakat, the alms tax, without formally challenging Islam. Many tribal leaders also made claims to prophethood; some even did so during the lifetime of Muhammad. The first incident of apostasy was fought and concluded while Muhammad still lived; a supposed prophet Aswad Ansi arose and invaded South Arabia; he was killed on 30 May 632 (6 Rabi' al-Awwal, 11 Hijri) by the Persian Muslim governor Fayruz al-Daylami. The news of his death reached Medina shortly after the death of Muhammad. The apostasy of al-Yamama was led by another supposed prophet, Musaylima, who arose before Muhammad's death; other centers of the rebels were in the Najd, Eastern Arabia (known then as al-Bahrayn) and South Arabia (known as al-Yaman and including the Mahra). Many tribes claimed that they had submitted to Muhammad and that with Muhammad's death, their allegiance was ended. Caliph Abu Bakr insisted that they had not just submitted to a leader but joined an ummah (أُمَّـة, community) of which he was the new head. The result of this situation was the Ridda wars.
The campaign against apostasy or the Ridda wars were fought and completed during the eleventh year of the Hijri. The year 12 Hijri dawned on 18 March 633 with the Arabian peninsula united under the caliph in Medina. Abu Bakr divided the Muslim army into several corps. The strongest corps and the primary force of the Muslims was the corps of Khalid ibn al-Walid. This corps was used to fight the most powerful of the rebel forces. Other corps were given areas of secondary importance in which to bring the less dangerous apostate tribes to submission. Abu Bakr's plan was first to clear Najd and Western Arabia near Medina, then tackle Malik ibn Nuwayra and his forces between the Najd and al-Bahrayn, and finally concentrate against the most dangerous enemy, Musaylima and his allies in al-Yamama. After a series of successful campaigns Khalid ibn al-Walid defeated Musaylima in the Battle of Yamama.
Expeditions to Persia and Syria
After Abu Bakr unified Arabia under Islam, he began the incursions into the Byzantine Empire and the Sasanian Empire. Whether or not he intended a full-out imperial conquest is hard to say; he did, however, set in motion a historical trajectory that in just a few short decades would lead to one of the largest empires in history. Abu Bakr began with Iraq, the richest province of the Sasanian Empire. He sent general Khalid ibn al-Walid to invade the Sassanian Empire in 633. He thereafter also sent four armies to invade the Roman province of Syria, but the decisive operation was only undertaken when Khalid, after completing the conquest of Iraq, was transferred to the Syrian front in 634.
Umar's reign (634–644)
Umar ibn al-Khattab (Arabic: عمر ابن الخطاب, romanized: ʿUmar ibn al-Khattāb, c. 586/590 – 644) c. 2 November (Dhu al-Hijjah 26, 23 Hijri) was a leading companion and adviser to Muhammad, and father-in-law by his daughter Hafsa bint Umar's marriage to Muhammad. He was appointed by a dying Abu Bakr to be his successor and took power on 23 August 634, becoming the second Muslim caliph after Muhammad's death. At least according to Laura Veccia Vaglieri, the expansion of Islam from an "isolated episode" in Arab history to an event of "worldwide importance" can be attributed to Umar's political skills.
Upon his accession, Umar adopted the title amir al-mu'minin (Commander of the Faithful) which later became the standard title of caliphs. During his 10-year reign, the Islamic empire expanded at an unprecedented rate. The new caliph continued the war of conquests begun by his predecessor, pushing further into the Sassanian Empire, north into Byzantine territory, and went into Egypt. These were regions of great wealth controlled by powerful states, but the long conflict between Byzantines and Persians had left both sides militarily exhausted, and the Islamic armies easily prevailed against them. By 640, they had brought all of Mesopotamia, Syria and Palestine under the control of the Rashidun Caliphate; Egypt was conquered by 642, and almost the entire Sassanian Empire by 643.
While the caliphate continued its rapid expansion, Umar laid the foundations of a political structure that could hold it together. He created the Diwan, a bureau for transacting government affairs. The military was brought directly under state control and into its pay. Crucially, in conquered lands, Umar did not require that non-Muslim populations convert to Islam, nor did he try to centralize government. Instead, he allowed subject populations to retain their religion, language, and customs, and he left their government relatively untouched, imposing only a governor (amir) and a financial officer called an amil. These new posts were integral to the efficient network of taxation that financed the empire.
With the bounty secured from conquest, Umar was able to support its faith in material ways: the companions of Muhammad were given pensions on which to live, allowing them to pursue religious studies and exercise spiritual leadership in their communities and beyond. Upon entering Jerusalem, Umar ordered that rubbish be cleared away from the mount of the al-Masjid al-Aqsa (compound) and that a mosque be built there. Jebran Chamieh writes that Muslim stories passed down after his death stress Umar's "asceticism, his care for the poor and public money. Tradition claims that he had a single threadbare dress thawb which he patched with leather whenever it was torn. The purpose of these tales was to emphasize his piety and abnegation, and that he did not take money from the treasury", It is however difficult to reconcile these stories of self-denial "with the fact that the other leading Companions amassed great wealth", and Umar's share of the spoils from the conquered lands was at least equal to their shares.
Umar is also remembered for establishing the Islamic calendar; like the Arabian calendar, it is lunar, but the origin is set in 622, the year of the Hijra when Muhammad emigrated to Medina.
While Umar was leading the morning prayers in 644, he was assassinated by a Persian slave, Abu Lu'lu'a Firuz. He appointed Suhayb ibn Sinan to lead the prayers in his stead.
Uthman's reign (644–656)
Uthman ibn Affan (Arabic: عثمان ابن عفان, romanized: ʿUthmān ibn ʿAffān) (c. 573 – 17 June 656), who became the third caliph at the age of 70, was one of the early companions, and son in law of Muhammad by marriage to two daughters of Muhammad and Khadija, Ruqayyah and Umm Kulthum. Uthman was born into the powerful Umayyad clan of the Meccan Quraysh tribe. Under his leadership, the empire expanded into Fars (present-day Iran), some of Khorasan (present-day Afghanistan), and Armenia. His rule ended when he was assassinated. Uthman is perhaps best known for forming the committee which standardised and canonised the Quran.
Election of Uthman
Before Umar died, he appointed a committee of six men to decide on the next caliph and charged them with choosing one of their own numbers. All of the men, like Umar, were from the tribe of Quraysh. His plan for choosing the next caliph has been criticized for its small size and unrepresentativeness, which excluded Muslims from Medina, Mecca, Taif, and other tribes; for his inclusion of a tie breaking seventh member who would be sure to veto Ali, and for instructions to execute committee members if the committee was deadlocked.
The committee narrowed down the choices to two: Uthman and Ali. Ali was from the Banu Hashim clan (the same clan as Muhammad) of the Quraysh tribe, and he was the cousin and son-in-law of Muhammad and had been one of his companions from the inception of his mission. Uthman was from the Umayyad clan of the Quraysh. He was the second cousin and son-in-law of Muhammad and one of the early converts of Islam. Uthman was ultimately chosen.
Reign of Uthman
Uthman reigned for twelve years as caliph. During the first half of his reign, he had been popular, while in the latter half of his reign, he met increasing opposition, led by the Egyptians and concentrated around Ali, who would succeed Uthman as caliph.
Uthman's most lasting project was the final compilation of the Qur'an. Uthman formed the committee which was tasked with producing copies of the Quran based on text that had been gathered separately on parchment, bones and rocks during the lifetime of Muhammad. Under his authority diacritics were written with Arabic letters so that non-native speakers of Arabic could easily read the Qur'an. Uthman sent copies of the sacred text to each of the Muslim cities and garrison towns and destroyed variant texts.
Despite internal troubles, Uthman continued the wars of conquest started by Umar. The Rashidun army conquered North Africa from the Byzantines and even raided Spain, conquering the coastal areas of the Iberian Peninsula, as well as the islands of Rhodes and Cyprus. Coastal Sicily was raided in 652. The Rashidun army fully conquered the Sasanian Empire, and its eastern frontiers extended up to the lower Indus River.
Assassination of Uthman
Uthman was generous in distributing booty and land to his relatives and fellow companions in the Quraysh tribe. Governors under his jurisdiction were accused of extravagance and excessive tax collection. This provoked jealousy and resentment among excluded Muslims, especially in Egypt and Iraq, at a time when the numbers and power of the Quraysh were being diluted by the vast new conquered lands and converts to Islam. Outraged at what they considered the nepotism and corruption of Uthman, rebels from the provinces marched on Medina and put Uthman's house under siege, giving Uthman a choice between abdication or death.
Early caliphs had no security force to protect them. They depended on tribal levies from the Arabs whose loyalty came from the deference due to the Caliph as a successor of Muhammad. When Uthman lost that deference, he had little left to protect him. Uthman refused the rebels' demand to abdicate, declaring instead that "it is easier for me to die than to disown a mission (the caliphate) that God has entrusted to me." He then returned to his room to read the Quran as the protesters broke into his house from the back and killed him.