Muslim Conquest: History, Causes, and Lasting Impact

Within a single century of the Prophet Muhammad's ﷺ passing, Muslim armies had reached the borders of China in one direction and the Atlantic coast of Spain in the other. This is one of history's most remarkable facts — and it raises genuine questions: How did this happen? What motivated it? And how should a Muslim today understand this chapter of their tradition?

What Were the Muslim Conquests?

The Muslim conquests — al-futuhaat al-islamiyya (الفتوحات الإسلامية), literally "the Islamic openings" — were a series of military campaigns carried out by early Islamic states that dramatically expanded the territory under Muslim political rule. Beginning after the Prophet's ﷺ death in 632 CE and accelerating under the Rightly Guided Caliphs, these campaigns transformed the Arabian Peninsula's young faith community into a civilization spanning three continents within roughly a century. At their height under the Umayyad Caliphate, the Muslim-ruled world was the largest empire on Earth.

Major Early Muslim Conquests at a Glance

Why Did the Conquests Happen?

The Religious Motivation: Carrying the Message of Tawhid

Early Muslim soldiers did not understand themselves primarily as empire-builders. They understood themselves as carriers of a message — the message of tawhid (تَوْحِيد), the absolute oneness of Allah.

The Quran granted permission to fight those who had persecuted the first Muslim community: "Permission [to fight] has been given to those who are being fought, because they were wronged — and indeed, Allah is competent to give them victory" (Surah Al-Hajj, 22:39). The early campaigns were framed as removing political obstacles to people hearing that message freely — not forcing belief, which the Quran explicitly forbids: "There is no compulsion in religion" (Surah Al-Baqarah, 2:256).

This theological foundation is essential context. The conquest was not primarily about racial superiority or resource acquisition. It was driven by a genuine conviction that the message of Islam was for all of humanity.

The Political Context: Two Exhausted Empires

At the moment Islam emerged, the two superpowers of the ancient world — the Byzantine (Eastern Roman) Empire and the Sassanid Persian Empire — had just concluded decades of ruinous warfare against each other. Both had depleted their treasuries, exhausted their armies, and alienated local populations through heavy taxation and religious persecution.

When Muslim armies entered Syria, Egypt, and Persia, they frequently encountered populations who did not fight back — or who actively welcomed the change in governance. The Muslim forces, by contrast, arrived with battle-hardened veterans, a unified command, and remarkable organizational discipline under leaders like Khalid ibn al-Walid, whom the Prophet ﷺ named Sayf Allah (the Sword of Allah).

How Conquered Peoples Were Treated

The early Muslim conquests were, by the standards of ancient warfare, notably restrained. Caliph Umar ibn al-Khattab personally entered Jerusalem on foot when it surrendered in 638 CE and issued a formal guarantee of security — aman — to its Christian and Jewish inhabitants:

"This is the assurance of safety which the servant of Allah, Umar, the commander of the believers, grants to the people of Aelia [Jerusalem]. He grants them safety for their lives, their property, their churches and crosses, the sick and the healthy of the city, and all the rituals belonging to their religion."

Non-Muslims in conquered territories were given dhimmi (ذِمِّي) status — protected subjects who retained their faith, their places of worship, and their internal legal systems. In exchange, they paid jizya (جِزْيَة), a poll tax that exempted them from military service and entitled them to state protection. This arrangement was not equality as we understand it today, but it was far more tolerant than the fate of conquered peoples under Rome, Persia, or later medieval European powers.

The Role of the Companions

The early conquests were led by some of the greatest figures of Islamic history — men who had prayed behind the Prophet ﷺ himself and carried his example into battle and into governance.

Khalid ibn al-Walid, arguably the most brilliant military commander in early Islamic history, was undefeated in more than 100 battles. Sa'd ibn Abi Waqqas led the decisive Battle of al-Qadisiyyah (636 CE) that ended the Sassanid dynasty. Amr ibn al-As negotiated the peaceful surrender of Alexandria. These were not merely soldiers; they were also the people who established mosques, courts, and markets in the lands they entered.

For a deeper look at the early Muslim community that produced these figures, our article on the early Muslim community explores the social and spiritual formation that made the companions who they were. And understanding how Islam spread reveals how military conquest was only one of several channels — trade, migration, and Sufi da'wah (outreach) also played essential roles.

Conversion Was Gradual, Not Immediate

A common misconception is that the military conquests produced mass immediate conversion. The historical record tells a different story. Egypt, for example, was conquered in 641 CE, but remained a majority-Christian society for several more centuries. Persia converted gradually over generations. Al-Andalus (Muslim Spain) maintained large Jewish and Christian communities throughout its 800 years of Islamic governance.

Islam spread not primarily through military force but through commerce, intermarriage, the appeal of Islamic ethics, and the work of traveling scholars and Sufi orders. Our broader piece on the expansion of Islam covers these multiple pathways in detail.

The Abbasid Turn: From Conquest to Civilization

By 750 CE, the Umayyad Caliphate gave way to the Abbasid, and the character of the Islamic world shifted. Baghdad became the capital — and the greatest city on Earth. The focus moved from military expansion to administrative governance, translation of Greek and Persian texts, and original intellectual production.

Muslim scholars during the Islamic Golden Age (roughly 750–1258 CE) made foundational contributions to algebra, optics, medicine, astronomy, philosophy, and geography. This was not a departure from the early conquests — it was their harvest. The vast, connected world created by the futuhaat allowed an unprecedented exchange of knowledge across cultures and traditions.

Our guide to the Islamic Golden Age covers this flowering in detail. And the question of how Islam spread from Arabia across the world shows how military, commercial, and intellectual factors worked together.

What the Muslim Conquests Mean for Muslims Today

Muslims today do not carry swords or govern empires. But the early conquests left a legacy that shapes Islamic identity in real ways.

They demonstrated that Islam was not a faith confined to Arabia or to a particular tribe. The companions who entered Jerusalem, Ctesiphon, and Cordoba were Arabs, Persians, Africans, and Byzantines — a community in which, as the Prophet ﷺ taught, no Arab had superiority over a non-Arab except through taqwa (God-consciousness).

They also left behind centuries of Islamic civilization — universities, hospitals, architectural wonders, and an intellectual inheritance that shaped the modern world. Understanding this history gives Muslims a richer sense of their tradition and a deeper appreciation for the obligation to contribute to human flourishing in their own era.

For early Muslim history grounded in scholarly sources, Yaqeen Institute's research papers on Islamic history and civilization are reliable and rigorous. And the Quran.com platform makes it easy to look up the specific verses that shaped the early community's understanding of justice, expansion, and the treatment of those outside the faith.

The DeenBack piece on daily dhikr habits reminds us of something the early companions modeled: those who changed the world were, first of all, people who remembered Allah consistently. And Demi Manifest on Islamic purpose and clarity explores what it looks like to draw on that same inheritance — not to rebuild empires, but to live with purpose.

Connecting History to Daily Practice

The companions who led the early conquests were also the people who prayed at night, wept in dua, gave generously, and treated their enemies with dignity where Islamic law required it. Their outward achievements grew from an inward orientation toward Allah.

That connection between character and contribution is not a relic of history. It is the ongoing invitation of Islam. Our guides to how to build Islamic habits and the importance of seeking knowledge in Islam offer practical steps for carrying that same spirit into a modern life.