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The rise of Islamic empires and states

Learn about the Arab Muslim conquests and the establishment of the caliphate.


  • Islam spread through military conquest, trade, pilgrimage, and missionaries.
  • Arab Muslim forces conquered vast territories and built imperial structures over time.
  • Most of the significant expansion occurred during the reign of the Rashidun from 632 to 661 CE, which was the reign of the first four successors of Muhammad.
  • The caliphate—a new Islamic political structure—evolved and became more sophisticated during the Umayyad and Abbasid caliphates.
Over a period of a few hundred years, Islam spread from its place of origin in the Arabian Peninsula all the way to modern Spain in the west and northern India in the east.
Islam traveled through these regions in many ways. Sometimes it was carried in great caravans or sea vessels traversing vast trade networks on land and sea, and other times it was transferred through military conquest and the work of missionaries. As Islamic ideas and cultures came into contact with new societies, they were expressed in unique ways and ultimately took on diverse forms.

Different trajectories

To begin to understand the rich history of Islam, let’s start with the historical context and events that led to Islam’s spread. For example, Islam initially spread through the military conquests of Arab Muslims, which happened over a very short period of time soon after the beginning of Islam. However, only a small fraction of the people who came under Arab Muslim control immediately adopted Islam. It wasn’t until centuries later, at the end of the eleventh century, that Muslims made up the majority of subjects of the Islamic empires.
The spread of Islam through merchants, missionaries, and pilgrims was very different in nature. These kinds of exchanges affected native populations slowly and led to more conversion to Islam. As Islamic ideas traveled along various trade and pilgrimage routes, they mingled with local cultures and transformed into new versions and interpretations of the religion.
Another important thing to note is that not all military expansion was Arab and Muslim. Early on in Islamic history, under the Rashidun caliphate—the reign of the first four caliphs, or successors, from 632 to 661 CE—and the Umayyad caliphate, Arab Muslim forces expanded quickly. With the Abbasids, more non-Arabs and non-Muslims were involved in the government administration. Later on, as the Abbasid caliphate declined, there were many fragmented political entities, some of which were led by non-Arab Muslims. These entities continued to evolve in their own ways, adopting and putting forth different interpretations of Islam as they sought to consolidate their power in different regions.
What are some of the ways in which Islam spread?
When did most conversion to Islam occur?

The first Arab Muslim empire

During the seventh century, after subduing rebellions in the Arabian peninsula, Arab Muslim armies began to swiftly conquer territory in the neighboring Byzantine and Sasanian empires and beyond. Within roughly two decades, they created a massive Arab Muslim empire spanning three continents. The Arab Muslim rulers were not purely motivated by religion, nor was their success attributed to the power of Islam alone, though religion certainly played a part.
Non-Muslim subjects under Arab Muslim rule were not especially opposed to their new rulers. A long period of instability and dissatisfaction had left them ambivalent toward their previous rulers. Like all other empires, the first Arab Muslim empires were built within the context of the political realities of their neighboring societies.
A depiction of Mohammed (top, veiled) and the first four Caliphs. From the Subhat al-Akhbar, a 17th-century Ottoman painting. Image credit: Wikipedia.
During the Rashidun caliphates, Arab Muslim forces expanded outward beyond the Arabian peninsula and into the territories of the neighboring Byzantine and Sasanian Empires. These empires were significantly weakened after a period of fighting with one another and other peripheral factions like the Turks, economic turmoil, disease, and environmental problems. The Arab Muslim conquerors were primed to take advantage of this; they were familiar with Byzantine and Sasanian military tactics, having served in both armies.
With the Byzantine and Sasanian Empires on the decline and strategically disadvantaged, Arab Muslim armies were able to quickly take over vast territories that once belonged to the Byzantines and Sasanians and even conquer beyond those territories to the east and west.
Most conquests happened during the reign of the second caliph, Umar, who held power from 634 to 644. The Rashidun caliphate constructed a massive empire out of many swift military victories. They expanded for both religious and political reasons, which was common at the time.
One political advantage the Rashidun caliphate held was their ability to maintain stability and unity among the Arab tribes. Distinct, feuding Arab tribes united into a cohesive political force, partially through the promise of military conquest. However, this unity was tentative and ultimately gave way to major divergences that disrupted state and religious institutions in the coming centuries.
How quickly did the Arab Muslim Empires spread?
What were some of the reasons the Byzantine and Sasanian Empires were vulnerable to attacks by the Arab Muslim conquerors?

A new political structure

The Rashidun can be credited for military expansion, but did Islam truly spread through their conquests? Significant conversion and cultural exchange did not occur during their short rule, nor were complex political institutions developed. It was not until the Umayyad Dynasty—from 661 to 750—that Islamic and Arabic culture began to truly spread. The Abbasid Dynasty—from 750 to 1258—intensified and solidified these cultural changes.
Dome of the Clocks, Umayyad Mosque, Damascus, Syria. The Dome was built in 780, while the mosque was completed in 715. Image credit: Wikipedia
Before the Umayyads, Islamic rule was non-centralized. The military was organized under the caliphate, a political structure led by a Muslim steward known as a caliph, who was regarded as the religious and political successor to the prophet Muhammad. The early caliphate had a strong army and built garrison towns, but it did not build sophisticated administrations. The caliphate mostly kept existing governments and cultures intact and administered through governors and financial officers in order to collect taxes.
The Rashidun caliphate was also not dynastic, meaning that political leadership was not transferred through hereditary lineage.1 During this period, it seems the Arab tribes retained their communal clan-based systems of choosing leaders.
However, to sustain such a massive empire, more robust state structures were necessary, and the Umayyads began developing these structures, which were often influenced by the political structures in neighboring empires like the Byzantines and Sasanians. Under the Umayyads, a dynastic and centralized Islamic political state emerged.
The Umayyads shifted the capital from Mecca to Syria and replaced tribal traditions with an imperial government controlled by a monarch. They replaced Greek, Persian, and Coptic with Arabic as the main administrative language and reinforced an Arab Islamic identity. Notably, an Arab hierarchy emerged, in which non-Arabs were accorded secondary status. The Umayyads also minted Islamic coins and developed a more sophisticated bureaucracy, in which governors named viziers oversaw smaller political units.
The Umayyads did not actively encourage conversion, and most subjects remained non-Muslim. Because non-Muslim subjects were required to pay a special tax, the Umayyads were able to subsidize their political expansion.
This map shows the extent of the Umayyad Empire in 750 CE. Image credit: Wikipedia.
The Umayyads did not come into power smoothly. The transition between the rule of the Rashidun and the first Umayyads was full of strife. Debates raged about the nature of Islamic leadership and religious authority. These conflicts evolved into major schisms between Sunni, Shia, and Ibadi Islam.
Ultimately, there were many factions that regarded the Umayyads as corrupt and illegitimate, some of whom rallied around new leaders. These new leaders claimed legitimacy through shared lineage with the prophet Muhammad, through the prophet’s uncle, Abbas. They led a revolt against the Umayyads, bringing the Abbasid caliphate to power.
The Abbasids were intent on differentiating themselves from their Umayyad predecessors, though they still had a lot in common. Abbasid leadership was also dynastic and centralized. However, they changed the social hierarchy by constructing a more inclusive government in a more cosmopolitan capital city, Baghdad. The distinction between Arab Muslims and non-Arab Muslims diminished, with Persian culture exerting a greater influence on the Abbasid court.
Dome of the Treasury, Umayyad Mosque, Damascus, Syria. The Dome was built in 789, while the mosque was completed in 715. Image credit: Wikipedia
Under the Abbasids, Islamic art and culture flourished. They are famous for inaugurating the Islamic golden age. Religious scholars, called ulema, developed more defined religious institutions and took on judicial duties and developed systems of law. It was also during Abbasid rule that many people converted to Islam, for a multitude of reasons including sincere belief and avoiding paying taxes levied on non-Muslims. As a result, Islamic culture spread over the Abbasids’ vast territory.
How did the Umayyad political structure differ from the Rashidun?
How did the Abbasid social hierarchy differ from the Umayyad social hierarchy?

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