The title Rashidun comes from the deeply ingrained belief[3] in Sunni Islam that the caliphs were 'rightly guided' (the meaning of al-Rāshidūn; الراشدون), endowed with superior piety and wisdom,[4] and therefore constituted a religious model (sunnah) to be followed and emulated.

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.

Apostasy (in the form of refusal to obey and pay revenue 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 Ta'if, and the Bani Abdul Qais of Oman.

The first incident of apostasy was fought and concluded while Muhammad still lived; a supposed prophet Aswad Ansi arose and invaded South Arabia;[23] he was killed on 30 May 632 (6 Rabi' al-Awwal, 11 Hijri) by Governor Fērōz of Yemen, a Persian Muslim.

[36] 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.

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.

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.

Demands to take revenge for the assassination of Caliph Uthman rose among parts of the population, and a large army of rebels led by Zubayr, Talha and the widow of Muhammad, Aisha, set out to fight the perpetrators.

[42][43][page needed] The Rashidun Caliphate expanded steadily; within the span of 24 years, a vast territory was conquered comprising Mesopotamia, the Levant, parts of Anatolia, and most of the Sasanian Empire.

The Persians once again concentrated armies to regain Mesopotamia, while Mithna ibn Haris withdrew from central Iraq to the region near the Arabian desert to delay war until reinforcement came from Medina.

The entirety of present-day Iran was conquered, followed by Greater Khorasan (which included the modern Iranian Khorasan province and modern Afghanistan), Transoxania, Balochistan and Makran (part of modern-day Pakistan), Azerbaijan, Dagestan (Russia), Armenia and Georgia; these regions were later re-conquered during Uthman's reign with further expansion into the regions which were not conquered during Umar's reign; hence, the Rashidun Caliphate's frontiers in the east extended to the lower river Indus and north to the Oxus River.

[101] Abu Ubaidah and Khalid ibn al-Walid, after conquering all of northern Syria, moved north towards Anatolia taking the fort of Azaz to clear the flank and rear of Byzantine troops.

In the frontier area where Anatolia met Syria, the Byzantine state evacuated the entire population and laid waste to the countryside, creating a no man's land where any invading army would find no food.

In return for a tribute of money and food for the occupation troops, the Christian inhabitants of Egypt were excused from military service and left free in the observance of their religion and the administration of their affairs.

[citation needed] The early caliphate naval conquest managed to mark long time legacy of Islamic maritime enterprises from the Conquest of Cyprus, the famous Battle of the Masts[116] up to of their successor states such as the area Transoxiana from area located in between the Jihun River (Oxus/Amu Darya) and Syr Darya, to Sindh (present day Pakistan), by Umayyad,[117] naval cove of privateer in La Garde-Freinet by Cordoban Emirate,[118] and the Sack of Rome by the Aghlabids in later era.

[119][120][121] The four Rashidun Caliphs (and companions of Muhammad) not only conquered large amounts of territory but established "a system of government" and formulated "political principles" for the Moslem Community" in the eyes of Muslim fundamentalists and Islamists, at least according to Jebran Chamieh.

"[124] The conquests begun under caliphs Abu Bakr and expanded under Umar resulted in an empire of vast size, covering a diversity of races, customs, types of government.

To deal with this diversity, Caliph Umar allowed the local administration of occupied countries to carry on much as before, (according to scholar Laura Veccia Vaglieri),[34] and confined himself to appointing a commander or governor (amir) with full powers, sometimes assisted by an agent (amil), responsible directly to the capital's empire in Medina, to take care of financial matters.

[125][c] According to historians Bosworth Marín and Ayalon, with the exception of Umar, who was appointed by Abu Bakr, the Rashidun caliphs were chosen by a small group of prominent members of the Quraysh tribe called shūrā (Arabic: شُـوْرَى, lit. 'consultation').

Capable men who would lead well were preferred over an ineffectual direct heir, as there was no basis in the majority Sunni view that the head of state or governor should be chosen based on lineage alone.

Madelung writes that Abu Bakr, acting as a shrewd politician, ensuring his selection as Muhammad's successor by avoiding the use of a shura (because it "would have backed hereditary success"), "sidelining" the Ansar and early "Companions of the Prophet" in favor of his supporters among the Meccan Quraysh.

Dhimmis were allowed to "practice their religion, and to enjoy a measure of communal autonomy" and were guaranteed their personal safety and security of property, but only in return for paying tax (jizya)[134] and acknowledging Muslim rule.

[178][179][e] The Rightly Guided Caliphate is also featured in other hadiths about endtimes in Sunan Abu Dawood and Musnad Ahmad ibn Hanbal, where it is foretold they will be restored once again by God in the time before Judgement Day.

[citation needed] In Sunni Islam, the application of the label 'rightly-guided' to the first caliphs signifies their status as models whose actions and opinions (Arabic: sunna) should be followed and emulated from a religious point of view.

[195] At the same time, it has been noted that the domination of Arabs over non-Arabs on an ethnic basis during Umar's reign and the widespread nepotism of Uthman's caliphate are in essential conflict with the call of Islam.

[54] In the Shia view, while direct revelation ended with Muhammad's death, Ali remained the righteous guide or Imam towards God, similar to the successors of the past prophets in the Quran.

Fred Halliday,[i] for example noting that "of the four caliphs, the first, Abu Baker, lived less than two years - too short a time to validate any political system - and the other three, Umar, Uthaman and Ali, were all murdered.

[212]Similarly, Shia view the companions, including the Rashidun Caliphs, as less than models of piety, instead accusing many of them of conspiring after the Prophet's death to dispossess Ali ibn Abi Talib and his descendants of the divinely ordained right to leadership.

[215] Chamieh and Ahmad Amin note earlier historians saw the Rashidun as mortals who possessed both great achievement and human weaknesses such as competition for political power and pursuit of worldly riches and pleasure.

[4][216] With the political and intellectual decline of the Abassid dynasty and rise of the religiously conservative Ahl al-Naql (People of Revelation), the idea that the Rashidun caliphate was a "utopia" that Muslims can recreate by imitating its (alleged) purity, took root.