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The Spread of Islam
Sep 1, 2010

There are several historical reasons for the astounding spread of Islam throughout Arabia and abroad after Muhammad’s death in 632 AD. These factors differed in degree depending on which Islamic leader, empire, or dynasty was in power. Although the religious sincerity and zeal of the Islamic powers varied greatly, some reflection of the Muslim theological past was needed – and I would argue was vital – to internally stabilize the Islamic world, which would be necessary for later conquests and expansion. I will be arguing that due to the ingenuity of those in power, general internal stabilization followed in the new Islamic world, which allowed successful Islamic military conquests to begin, and Islam soon became a more likely entity to spread during the period of 630–1683. I will also be emphasizing how Islamic leaders and empires regularly referred back to the religious principles established by the Prophet and the early Caliphs, which justified their claims to power and fueled a desire to expand realms.

The spread of Islam would obviously not have occurred without its Prophet, Muhammad, who was able to win support for his spiritual and political status within Arabia in the early seventh century. After having claimed to receive divine revelations, Muhammad slowly acquired a small following and eventually some seventy families had converted to Islam. However, not all of his contemporaries were convinced of the genuineness of his message. This was especially true of the pagan rulers of his Quraysh tribe in Mecca. Consequent persecutions caused the early Muslims to flee to Yathrib, which was located 250 miles north of Mecca. Yet, what appeared to be a backward move for the early believers actually benefited them and their religion as the tribes around Yathrib were enthralled by Muhammad’s spiritual vision and pledged allegiance to the ummah (community). A series of conflicts between the Quraysh and Muslims climaxed in 630 when the Quraysh broke an earlier peace treaty that had been established. This saw Muhammad march upon Mecca with 10,000 men and take the city without bloodshed. He then destroyed the idols around the Kabah and rededicated it to God. By the time of Muhammad’s death in 632, as Karen Armstrong explains, “almost all the tribes of Arabia had joined the ummah as Confederates or as converted Muslims.” As history will show, this was not the end of this remarkable series of events. For unification of Arabia would not cease at the death of the founder of Islam but would rather dramatically gain momentum through his successors, the Caliphs.

With the combination of three important factors: unification, conquest, and religious zeal, the early Caliphs were able to consolidate Muslim rule in Arabia and prepare a launching pad for further conquests. This initial spread of Islam was so rapid that, as H. U. Rahman explains, “in less than one century after the death of the Prophet Muhammad in 632 AD, Muslim rule covered more of the earth than had the Roman Empire at its peak.” This unification did not however happen overnight, and it must be emphasized that Islamic rulers always had much division to contend with. The first Caliph, Abu Bakr, had the difficult job of uniting all of the tribes that had forsaken their allegiance to the ummah after Muhammad’s death. Yet through political, theological, and at times military coercion, Abu Bakr was able to completely unify Arabia before his death in 634. Secondly, despite the assassinations of the next three caliphs – Umar, Uthman, and Ali – which characterizes the bloody period that ensued, the spread of Islam continued to gain momentum as successful military campaigns were carried out abroad. From 634–44, the Caliphate of Umar had conquered Jerusalem, controlled Iraq, Syria, Palestine, and Egypt, and defeated the Persian Empire. Furthermore, in Uthman’s reign (644–50), Muslims conquered Cyprus, Tripoli in North Africa, and established Islamic rule in Iran, Afghanistan, and the Sind region. The above two methods of internal unification and successful conquest led to the establishment of the Islamic world during the seventh century, and the speed in which it accomplished this announced to the world that Islam was here – and here to stay.

The third explanation of the rapid spread of Islam throughout Arabia and beyond was – most importantly – the religious zeal of the leaders, soldiers, and general Arab population. Plainly put, without being fuelled with a sense that God was on their side, the Muslim conquests would have fallen far short of their eventual reality. Tamara Sonn explains that the basic tenets of Islamic faith captivated the people and structured Islamic life in Medina, and it was around these practices and core values that the early Muslim community was built. Francesco Gabrieli supports Sonn and places a heavy emphasis on religion as the principal factor underlying and motivating the Arab conquests. Indeed, it is hard to imagine any group achieving geographical expansion without a clear goal and purpose; for the Mongols of the thirteenth century it was a brutal ideological reason, whilst for the Muslims it was the feeling that they were being divinely guided.

Nevertheless the spread of a religious or ideological ideal can only be truly successful if those whom it is trying to gain submission from are disillusioned or unhappy with their own contemporary world. This was the case for the many thousands of people under Byzantine rule. We find that a great number gladly adhered to the conquering Islamic rulers and Quranic law as they found protection and benefits that had not been attained under Byzantine rule. Many minorities had become increasingly dissatisfied with the Byzantine regime due to their insecurities of being persecuted and instead came to favor the secure Islamic rulership who allowed autonomy for minority groups if their taxes were paid. The preference of many of the conquered peoples to favor Islamic rule enabled the Islamic Empire to remain politically stable, which is a prerequisite for any group wanting to expand its geographic borders.

Turning back the clock to the infant stages of Islam, we find that the Muslims were fraught with political struggles for power. With factions developing within the Islamic world following Ali’s assassination (the fourth Caliph) in 661, the unity and prosperity of the new Islamic Empire became threatened. However, it was the way that the Muslims were efficiently able to get back on their feet and consolidate unity that saw these power struggles, which had the potential to dismantle Islamic hopes for expansion, averted. The Islamic world needed a leader who could unite as many of these factions together as possible, and this stability came with the establishment of the Ummayad Dynasty through Muawiyyah I. He ruled from 661–80 and was the first Caliph to move his capital away from Medina, transferring it to Damascus. However unpopular this move was, R. Stephen Humphreys explains that Muawiyyah I saved the Muslim Empire from disintegration as he was, “the only man with the political and military resources available to restore unity within the realm of Islam.” Although the Umayyad period is typically characterized by political and military success, the Umayyad rulers did not forget its founding religion. According to Karen Armstrong, Muawiyyah I was simply “a religious man and a devout Muslim.” Furthermore, a statement of Islam’s superiority to past religions was symbolically made through the establishment of the Dome of the Rock, which was completed at Jerusalem in 691 under Caliph Abd al-Malik. This spiritual construction shows that Islamic rulers could not go forward unless they acknowledged the close relationship between conquest and the Muslim religion, and this was done most emphatically with the construction of this monument.

Despite geographical consolidations made by the early Umayyad Caliphs, discontent remained within the Islamic world with several extremist groups emerging regularly in Islamic culture. This was perhaps a catalyst for Umayyad leaders having a more political conception of Islam than did previous rulers. Although the discontentment of factions within the Islamic world, such as the Shias, could not be eradicated, internal stability generally emerged at the commencement of the Umayyad Dynasty. Paul Lunde explains that the pacification of the central lands under early Umayyad rulers enabled them to focus primarily on conquest so that the spread of Islam could continue. Furthermore, according to Armstrong, conquest was able to be successfully waged during al-Walid I’s reign between 705–715 where the Umayyad dynasty reached its peak and the Muslim armies continued the conquest of North Africa, and established a kingdom in Spain. However, even though the Umayyad Dynasty had expanded its Islamic borders throughout the Arab world, its power soon declined, as internal friction had finally reached unmanageability. Then, the Umayyads – somewhat inevitably – succumbed to the overwhelming power of the Abbasids in 750.

Even though the overthrow of the Umayyad family by the Abbasids was horrific and angered many, this brutal act did not slow the continual geographical or economical gains of Islam. In fact, at the height of Abbasid power in 800 (who had moved the Islamic capital to Baghdad in 762) only Constantinople and Xian, the capital of the great T’ang China, rivaled Baghdad’s wealth. Although military might was the predominant vehicle of Islamic power, the strength of Muslims at the zenith of Abbasid power in the ninth century was represented through a great cultural renaissance which took place in literary criticism, philosophy, poetry, and science. This marked the beginnings of “Muslim genius” as individuals such as Abu Bakr Al Razi (864–925) studied medicine and uncovered unique contraceptive methods; and Abu Nasr Al Farabi (870–950) incorporated logic and politics into philosophy. As Armstrong explains, such was the grandeur of this era that the Muslim scholars made more scientific discoveries during this time than in the whole previously recorded history put together. Hence, these examples symbolize the prestige of the superpower Abbasid Empire of the old world, which asserted itself not only through military conquests but through cultural and scientific discovery.

However, despite the Abbasid period reaching new heights in regards to its geographical expansion, it too slowly declined in prestige from about 935 and would soon be unable to hold off a young and powerful group of Muslims in the centuries to follow: the Turks.

Before the success of one final Islamic Empire is discussed, it is important to reflect on several other specific reasons why Islam spread so rapidly throughout Arabia and to the whole world. Three of these deserve particular mention. First, the Caliphs and Muslim rulers were willing to use existing administrative structures to enforce laws, and it was not uncommon for non-Islamic officials to be used in high places within a conquered society. Second, there was seldom force or coercion used from Islamic forces once a military campaign was successful. As Francesco Gabrieli explains, the traditional theory of the conquests being characterized merely by Bedouin neophytes of Islam rushing from their desert birthplace to convert other nations with the sword has been completely dismissed by modern historiography. In fact, Arabs were quite content with their passive non-Muslim subjects known as dhimmis (those who were second-class citizens under Islamic law, yet protected under this status) and no real effort was made to convert them. This hands-off approach actually led to an increase in Islamic converts regularly throughout the Islamic Empire as individuals were pleased to make their own decision about religion, which is something that had not been afforded them under Byzantine rule.

Finally, further comparisons between Byzantine Christianity and Islam highlight how many became turned off by Christendom but enthusiastic and inquisitive about Islam. Christianity had become heavily clericized by the seventh century and appeared to be exclusive, whilst Islam appealed to individuals by offering unparalleled simplicity through its core principles. According to Abul-Fazl Ezzati, the five pillars of Islam, when compared to Christian orthodoxy, “replaced complexity of religious doctrines with simplicity, trinity with unity, empty theological discussions with concrete observation and fundamental analysis.” Moreover, the extent and rapidity of the success of Islamic military conquests had Muslims feeling that there was something divine aiding their cause. Zealous Muslims and their missionary activities always went hand in hand with the success of Islam and this sense of mission motivated Muslims to assist the expansion efforts in whatever way they could. Hence, Islam appealed to many contemporaries’ needs and with the lure of further expansion, many felt that Islam was the path for the future.

With this understanding in mind, we can finally return to the last great Islamic Empire of the ancient world through looking at the Ottoman Empire. Although Islam had by no means died out in terms of its expansion after Abbasid rule, it had clearly slowed by the fourteenth century. As Armstrong explains, from 935 onwards, “the caliphs no longer (wielded) temporal power but merely (retained) a symbolic authority. Real power now resided with the local rulers, who established dynasties in various parts of the empire.” Moreover, with the addition of the Mongol raids, which began in 1220, Islamic cities became desolate and the spread of Islam was curtailed for the first time in centuries as attention was turned to internal frontiers. However, a final thrust of Islamic expansion would occur through the Ottoman Empire, who slowly consolidated its own power in Anatolia, and by the late fourteenth century had begun to threaten Europe. One of the early Sultans, Murad I (1360–1389), had become the most powerful of the western Muslim rulers and this led to the name of the Ottomans symbolizing hope for a reunified Islamic empire. This hope was fueled by geographical gains made through military expansion by several Ottoman Sultans, such as Murad I (1421–1451), who asserted Ottoman power against Hungary and the West and by 1453 his successor, Mehmed II, who had conquered Constantinople, changed its name to Istanbul, and made it the Ottoman capital. Accordingly, the Ottomans had recommenced Muslim expansion and would look to achieve something past Islamic Empires could not – to successfully challenge Western Europe.

Ottoman expansion continued with Suleiman the Magnificent (1520–66) whose Empire, after conquering Hungary in 1526, had become the greatest power in Eastern Europe. It is important to note here that Suleiman saw the consolidation of Islamic values as the key to his military successes. As Jason Goodwin explains, Suleiman, “oversaw the most detailed codification of sultanic and Quranic law that had ever been known in an Islamic state.” Hence, although the Ottoman Empire did not represent all Muslims, it is clear that great Sultans such as Suleiman did not forget the founder of their religion as they saw themselves as a genuine continuation of early Islamic history. Justin McCarthy puts it clearly for us – “the base of the Ottoman Empire was Islam. Religion was intimately bound up with the ideology and legitimacy of the government … Their Empire was always styled a Muslim empire, one in the line of Islamic empires that had included the Umayyads, the Abbasids, and the Seljuks.” We see once again here, this time under the rule of the Ottomans, that legitimacy and support of a great Islamic Empire went hand in hand with a reflection on the spiritual past of the Muslim tradition.

Nevertheless, during the latter stages of Ottoman rule, the sultans began looking too far outwardly and neglecting inner spirituality, which deadened the degree of support that Muslims would give it. This empire fatally climaxed when the Ottomans looked to secure further lands in Europe. Their efforts fell horribly short, and they lost a vital battle to the coalition of the Holy League in 1683 at Vienna. When they were forced to humiliatingly sign the Treaty of Carlowicz in 1699, they had to yield Ottoman Hungary to Austria, which was the first major Ottoman reversal. Although the Empire did not crumble overnight, this point marks the end of Ottoman expansion – and indeed Islamic expansion – and the beginning of its slow decline.

The powerful Islamic dynasties and empires finally came to an end with the demise of the Ottoman Empire. Yet the legacy that both it and previous rulerships had left behind was remarkable geographical expansion, which had emanated from a small tribe in Arabia. The spread of Islam was orchestrated through the close connection of most Muslims and their leaders to an Islamic way of life, which gave them a sense of purpose for their conquests and expansions. It is important to understand that this was not always done smoothly; the overthrows of Islamic Empires did not always happen peacefully and blood was often internally shed in order to propel a fresher and stronger willed Islamic group forward. Although much internal strife was a common characteristic of the Islamic Empires, the historical reality shows us that enough of the Muslim population was willing to forget past disagreements and get on with a common cause of conquering peoples and gaining territory. Yet the key to all of this success was surely the religious foundation of the Prophet and the early Caliphs. Through future Islamic rulers regularly reminding their adherents of their Prophet and of his message, the Muslims felt as if they were part of something greater than themselves. Despite religious zeal fluctuating from time to time, Islamic faith would always seem to be reinvigorated which led to grand Empires being established and Islamic history being created.

Paul Kearns has a major in history and English from Monash University, Melbourne.


1. Karen Armstrong, Islam: A Short History, New York, 2000, p. 12.

2. Ibid, 23.

3. H. U. Rahman, A Chronology of Islamic History: 570-1000 ce, London, 1989, p. vii.

4. Tamara Sonn, A Brief History of Islam, Oxford, 2004, p. 23.

5. Armstrong, 2000, pp. 27, 29.

6. Ibid, p. xiv.

7. Sonn, 2004, p. 22.

8. Francesco Gabrieli, Muhammad and the Conquests of Islam, London, 1968, p. 104.

9. Sonn, 2000, pp. 25, 34.

10. R. Stephen Humphreys. Mu‘awiya ibn Abi Sufyan: From Arabia to Empire, Oxford, 2006, p. 84.

11. Armstrong. 2000, p. 42.

12. Ibid, p. 44.

13. Gerald R. Hawting. The First Dynasty of Islam: The Umayyad Caliphate AD 661-750, London, 1986, p. 2.

14. Paul Lunde. Islam, London, 2002, p. 52.

15. Armstrong, 2000, p. 50.

16. Lunde, 2002, p. 56.

17. Akbar S. Ahmed. Discovering Islam: Making Sense of Muslim History and Society, London, 2002, pp. 44-5.

18. Armstrong, 2000, p. 56.

19. Ibid, p. 54.

20. Gabrieli, 1968, p. 105.

21. Ibid, p. 115.

22. Abul-Fazl Ezzati. An Introduction to the History of the Spread of Islam, London, 1978, p. 43.

23. Ibid, p. 3.

24. Armstrong, 2000, p. xix.

25. Sonn, 2000, p. 78.

26. Patrick Kinross. The Ottoman Centuries: The Rise and Fall of the Turkish Empire, New York, 1979, p. 187.

27. Jason Goodwin. Lords of the Horizon: A History of the Ottoman Empire, New York, 1998, p. 83.

28. Justin McCarthy, The Ottoman Turks: An Introductory History to 1923, London, 1997, p. 106.

29. Armstrong, 2000, p. xxvi.