How can the expansion of Islam in the seventh century best be accounted for?

By: Manuela Medeiros

The seventh century was an eyewitness to the meteoric rise of Islam from an insecure monotheistic movement in the Arabian Peninsula to a transcontinental empire stretching from the exotic coast of India to the depths of the Atlantic Ocean. By the end of the century, the Islamic Caliphate had recouped the Sassanian Empire and wrested vast territories from Byzantium. This expansion, within geographical celerity and ideological impact—has sparked debate among scholars for centuries. Was it primarily due to military conquest, political opportunity, or religious appeal? This essay argues that the expansion of Islam in the seventh century is best explained through an interplay of military strategy, political conditions, economic motivations, and the compelling nature of Islam’s religious and social values. These factors, acting in the concert, enabled Islam not only to spread swiftly but to take root across diverse cultures and societies. 

Marshall Hodgson proposed that “Islamic history must be understood in its full complexity, as a religious, political, and cultural force.” (Hodgson 143) Thus, to properly account for the Islamic expansion in the seventh century, one must fathom the context of the Arabian peninsula.

Tribalism characterized pre-Islamic Arabia, lacking any central governmental framework (Crone 135). Allegiance belonged to clan and tribe, and conflicts between tribes were frequent. This wrought a void of power that Islam was legally and morally equipped to occupy. Starting in 622 CE, the Prophet Muhammad's leadership in Medina established a particular model of governance that combined tribal allegiance with religious devotion (Donner 44)—successfully creating the first Islamic state. Muhammad was not solely a prophet, but also a politician. His achievement in creating coalitions among conflicting tribes in Medina via the Constitution of Medina established the foundation for a multi-tribal Islamic political entity (Donner 76). By adopting a mesh of strategic treaties, military measures, and social changes, Muhammad swiftly brought a significant portion of the Arabian Peninsula under Islamic regime up until his passing in 632 CE. 

Fig 1. A map illustrating the rise and expansion of early Islamic caliphates from the Prophet Muhammad until the 9th century.

From charitable giving (zakāt), egalitarianism (at least in spiritual terms), and support for orphans and the underprivileged–Islam was rewriting social norms. With the provided ideological structure for domination and collaboration, Islamic principles offered a supra-tribal identity that united countless groups under a shared purpose, integrating tribal identities into the broader ummah (community of believers) and promoting unity (Donner, Muhammad and the Believers 44).  

Throughout the sixth century, Arabia hosted a wide spectrum of beliefs: polytheism, Christianity, Judaism , Zoroastrianism and Hanif monotheism. Within that context, Arabs were already disillusioned with polytheism and attracted to monotheistic ideas. Islam’s emphasis on moral principles, social justice, and a direct relationship with God that resonated deeply in a thirst for religious reform (Crone 135).  

Following the Prophet’s passing, the Rashidun (Rightly Guided) Caliphate (632-661 CE) and then the Umayyad Caliphate (661-750 CE) oversaw the bulk of Islamic territorial expansion. Their triumph cannot be solely attributed solely to religious ardour. It was a matter of opportunity, skill, and historical contingency. 

In regard to the Byzantine and the Sasanian empires, both were weakened by decades of mutual warfare, plague and internal dissent. The Sassanians collapsed entirely by 651 CE, while Byzantium lost control of Syria, Palestine, Egypt and North Africa. Local populations, particularly Monophysite Christians and Jews, were often ostracised from their rulers and viewed Muslim armies not as conquerors but as liberators who had considerably more religious tolerance and lower taxation.    

Arab armies were bound by size but highly mobile and well-adapted to desert warfare. Commanders like Khalid ibn al-Wadid used hasty cavalry tactics and remarkable knowledge of local terrain to outmaneuver larger, better-equipped opposing forces as illustrated by the tactics employed in the Battle of Yarmouk (636 CE) and Qadisiyyah (636 CE), both decisive victories that broke Byzantine and Persian resistance, respectively (Kennedy 88). 

While the idea of jihad has been interpreted in many ways, in the seventh century, it offered a religious basis for military growth. Combatants were frequently assured lively incentives following their duty, and the gains from conflict were divided, rendering involvement both materially and spiritually appealing. On the other hand, numerous conquests were more pragmatic than based on ideology. 

The world of conquest and expansion was not only limited to militia–it amounted to economics as well. Once controlled by the Byzantines and the Sassnians, the lucrative routes were effectively dominated by the early Caliphate (Crone 135). From Damascus to Alexandria, and later Baghdad–those key commercial routes were quickly coming into Islamic authority and the Caliphate found itself at the heart of international trade linking the East and the West. Enabling the dissemination of Islamic culture, language and administrative practices–these elaborate trails also brought wealth in the form of taxes and spoils. 

Moreover, economic incentives were systematically institutionalized. The introduction of jizya (a tax levied on non-muslim crowds) and the kharaj (land tax) set the stage for a strong economic rationale for preserving religious identity and diversity within the empire (Crone 135). Converts to Islam were exempts for jizya, which, while encouraging conversion, also reinforced the pragmatic coexistence of different faiths within the Islamic territories. The administrative adoption of diwan registers-bureaucratic systems adapted from Persian and Roman traditions–allowed for efficient tax collections, resource allocation and military organisation.   

The elite and military veterans of Arabian society were often granted land in conquered land, which not only secured loyalty but also incentivised settlement and long-term integration. These economic reforms ensured that Islamic rule was not only sustainable but also attractive, encouraging cooperation from local populations and former elites. As Patricia Crone observed, “Islam spread not just on the tip of a sword but also by the promise of a more equitable and efficient system of governance.”

Despite the remarkable military and economic contributions to its expansion, the religious and ethical message of Islam was a foundational element of its spread. The unity of God (tawhid) (The Qur’an 112:1-4), the brotherhood of believers, and personal accountability of Islam's theological emphasis before God resonated with diverse crowds, in particular those who felt unsatisfied with hierarchical complexities and doctrinal divisions amongst existing religions (Crone 135). 

Through the concept of ahl al-kitab (people of the book), allowed Islam to offer a more straightforward creed and tolerance of other monotheistic faiths–which was different to the Byzantine Empire, where theological disputes such as the nature of Christ's birth often resolute in persecution. This inclusivity was host to cultural integration rather than obliteration (Cook 59). Gradually, Islam was then adopted not at the point of the sword but through trade, intermarriage, administrative service, and intellectual exchange. Later seen as vehicles of social mobility and prestige, the Arabic language and Islamic culture were seen as symbols of innovation and growth. 

Written in the eloquent and poetic language of Arabic–the Quran itself became a literary and cultural magnet under Islamic rule expansion. After facilitating the standardisation of language, laws and education–the Quran's linguistic beauty and ethical vision provided a powerful unifying cultural force. Cultural and ideological stability across vast and ethnically diverse territories was further then maintained (Cook 59). 

As the empire expanded, coupled with the codification of the Qur’an in a written and recited form and the spread of Arabic language, the Islamic identity in the social and intellectual fabric became embedded into its empirical profile. Through mosque-based education, Qur’anic schools, and the translation of ancient texts into Arabic, Islam positioned itself not merely as a religious tradition, but as a comprehensive civilisational force (Cook 59). 

By being incentivised by cultural prestige, administrative benefits, and sincere spiritual appeal–conversion was often gradual. Thus, the religious and ideological coherence of Islam helped solidify its dominance. Guided by the adaptability and universalism embedded in Islamic doctrine, mass conversions did not occur immediately in Persia and North Africa but instead, unfolded over decades.

An inspiration to many diverse interpretations from historians across different schools of thought and centuries–the expansion of Islam was emphasized by a spectrum of narratives. In spite of earlier accounts of emphasized religious zeal or divine providence, multi-causal explanations alongside balancing material conditions, ideological appeal, and geopolitical crisis are preferred by the modern scholarship. 

A redefinition of the relationship between religion and governance is argued by history; Islam's fusion of ethical monotheism with statecraft created a “new kind of polity”, Hodgson argues. Rather than viewing expansion through a solely military lens, in his seminal work The Venture of Islam, underscores the civilizational scale of the birth of Islam. An avid outliver of its Arab origins, the early caliphate's capacity to unify diverse tribal and urban elements under a coherent moral order, created what was a portable and translatable model of governance (Crone 135).  

Through the legitimization of ideology and the binding of social force–the notion of umma (a divinely ordained community of believers) was contended by Fred Donner in The Early Islamic Conquests. Alongside political consolidation, a gradual solidification of its religious character emerged as a “believers’ movement” within the alternate suggestion that Islamic history was not to be solely looked at by a religious lens. 

Owing more to its ideological structure and Muhmmads charisma than to pre-existing economic frameworks, Patricia Crone, while critical of certain traditional Islamic accounts, challenges the assumption that Mecca was a major trading hub in Meccan Trade and the Rise of Islam. Whilst maintaining tribal loyalties through the distribution of ghanimah (spoils) and military stipends (‘ata’), Crone emphasizes the strategic brilliance of the early caliphs creating a system that simultaneously incentivized both loyalty and expansion. 

Narrated by a leading authority on early Islamic history, Hugh Kennedy frames the seventh-century conquests as a remarkable feat of coordination. Whilst respecting the significance of the institutional flexibility of the caliphate, Kennedy underscores the strategic pragmatism of commanders such as Khalid ibn al-Walid and Amr ibn al-’As (Kennedy 88). With an overwhelmingly remarkable capacity to adapt Roman and Sassanian administrative practices, Islam's successes with co-opting local elites, maintaining tax systems, and preserving social hierarchies were expedient–greatly contributed to its expansional success. 

Serving as a symbol of cultural and legal unification, the Quran's importance is stressed by Michael Cook in The Koran: A Very Short Introduction. After defining community boundaries, regulating economic transactions and establishing prototypes for conflict resolution–the Quran served not only as a scripture but as a catalyst to the spread of Islam. 

Driven by a rather growing scholarly consensus that Islam's expansion was diverse, a hypothesis that institutional pragmatism, historical opportunity, dynamic leadership and coherent ideology is birthed. Whilst playing a critical role in the sustained growth of the early Islamic world, the religious alongside military and economic aspects of Islam's rise were mutually reinforcing.

Such an expansion was not a historical accident or caused by a singular factor–whether it was military prowess or religious fervour–the Islamic expansion was the product of external opportunity and a unique convergence of internal cohesion. Offering a rich context of promised justice, unity, and moral clarity–Islam emerged in a politically and religiously fluid Arabian milieu. Islam was beyond a theological doctrine, it was a new socio-political order (The Qur’an 4:135). From the Prophet Muhammad to the Rashidun and Umayyad caliphs, the early Muslim leadership was capitalised on geopolitical understanding, sophisticated military strategy and pragmatic policy (Donner 76).  

While it is tempting to attribute the Islamic expansion purely to conquest, such a view fails to recognise the depth of transformation that occurred in its wake. The receptiveness of local populations, internal divisions within neighbouring empires and their decline–molded military victories. Yet Islam's power transcended conquest. From the Coptic Christians of Egypt to the Zoroastrians of Persia–Islam's institutional adaptability allowed it to resonate across different cultures. By maintaining relative religious tolerance and the integration of existing administrative systems, the early caliphate helped facilitate the transition from empire to civilisation. 

Illuminated by a spectrum of historical insight, the complexity behind this meteoric rise, summons an urge to view early Islam not merely as a faith, but as a transformative force. From Donner to Hodgson, it was precisely this multidimensionality that made Islam's expansion not only rapid, but everlasting.  

In the final analysis, the best account of Islam’s seventh-century expansion is one that embraces its intricacy. It was the symbiosis of sword and scripture, statecraft and spirituality, contingency and conviction, that enabled a small desert movement to become one of the most influential forces in world history.

Works Cited 

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6. Cook, M A. The Koran : A Very Short Introduction.   Oxford, England ; New York, Oxford University Press, 2000.

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8. Crone, Patricia. Meccan Trade and the Rise of Islam. Princeton University Press, 1987.

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10. Donner, Fred M. The Early Islamic Conquests. Princeton University Press, 1981.

11. Hodgson, Marshall G. S. The Venture of Islam: Conscience and History in a World Civilization. Vol. 1, University of Chicago Press, 1974.

12. Kennedy, Hugh. The Great Arab Conquests.      Weidenfeld & Nicolson, 9 Dec. 2010.