Early Muslim conquests

• 1. Introduction

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  The early Muslim conquests began in 622 when Muhammad established the first Islamic state at Medina, a small city in the Arabian Peninsula. Within a single century, armies fighting under the banner of Islam had pushed from the Indian subcontinent in the east all the way to the Pyrenees in the west. At their height, the caliphates ruled an estimated 13 million square kilometres of territory. Scottish historian James Buchan measured that achievement against history's other great conquerors and concluded that in speed and extent the first Arab campaigns were matched only by those of Alexander the Great, and that they proved more lasting. How did a region long dismissed as a backwater produce one of the most far-reaching military expansions the world had ever seen? The answer lies in a collision of failing empires, a new religion's political energy, and a peninsula whose warriors had been rehearsing for this moment without knowing it.

• 2. Two Exhausted Empires

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  For decades before the conquests, the Sasanian and Byzantine empires had been grinding each other down in a prolonged series of wars. Those conflicts ended with a Byzantine triumph: Emperor Heraclius reclaimed all lost territories and returned the True Cross to Jerusalem in 629. Yet neither empire had time to recover. Heraclius had framed his campaign against Zoroastrian Persia as a holy war, using splinters of wood said to come from the True Cross to inspire his soldiers. The effort was total and the cost immense. Historian George Liska observed that the unnecessarily prolonged Byzantine-Persian conflict opened the way for Islam. Compounding the military exhaustion, recurring outbreaks of bubonic plague, the Plague of Justinian, ravaged densely populated areas and blocked both empires from conscripting fresh troops, while Arab armies could draw recruits from nomadic populations unaffected by the same outbreaks. When Muslim forces arrived, James Howard-Johnston compared their advance to a human tsunami. The Sasanian civil war of 628-632 accelerated the collapse further by eroding the political confidence of the Persian elite, who came to suspect the ruling dynasty had forfeited divine favour.

• 3. Arabia Before the Conquests

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  Southern Arabia had for thousands of years sat at the centre of an international trading network linking Eurasia, Africa, Europe, the Middle East, India, and China, with the spice trade at its heart. Yemeni sailors travelled the Red Sea to Egypt and crossed the Indian Ocean to India and down the east African coast. That prosperity began to crack when the Marib Dam was destroyed by an earthquake around 450 AD, setting back the valley irrigation systems of Yemen. Then the conversion of the Mediterranean world to Christianity sharply reduced demand for frankincense and myrrh, which had been widely used in religious ceremonies. The economic slump that followed helped create the impression of Arabia as a backward region, obscuring its older sophistication. Tribal society remained divided along clan lines, with the most important fault running between the southern and northern tribal associations. Both the Byzantine and Sasanian empires competed for influence by sponsoring client kingdoms: the Lakhmids in what is now southern Iraq and northern Saudi Arabia served Persia, while the Ghassanids aligned with Byzantium. In 602 the Persians deposed the Lakhmids to take over their own southern frontier, a move that left Persian defences overextended. The only other significant military force on the Peninsula, the Himyarite Kingdom of South Arabia, had already dissolved by the mid-6th century. By the mid-630s, a newly united Arabian Peninsula stood at its greatest relative power in living memory, while its potential opponents were at their weakest.

• 4. Campaigns Across Three Continents

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  Khalid ibn al-Walid, who had converted to Islam around 627 and became one of Muhammad's most successful generals, commanded the Arab force that defeated a major Byzantine expedition at the Battle of Ajnadayn in 634. Ibn al-Walid had been fighting the Sasanians in Iraq when he led his force on a march across the desert to hit the Byzantines from the rear. After a six-month siege, the Arabs took Damascus, and when Heraclius briefly retook it, the Arabs won it back after their victory at the Battle of Yarmuk in 636. Jerusalem surrendered in 638; Caliph Umar accepted the garrison's terms and permitted the Church of the Holy Sepulchre to remain, praying on a prayer rug outside rather than inside the church. In Egypt, the general Amr ibn al-As launched his campaign on his own initiative in 639. Rather than heading for the capital Alexandria, he targeted the fortress of Babylon, located at what is now Cairo, intending to split the Nile valley in two. The garrison of Babylon surrendered on the 9th of April 641 after a siege left it starving, and Alexandria capitulated in September 642. Historian Hugh Kennedy judged the conquest of Egypt the swiftest and most complete of all the early Muslim conquests. In Persia, the decisive blow came at the Battle of al-Qadisiyyah in 636, fought over several days by the banks of the Euphrates in what is now Iraq, where the Persian force was annihilated. The last Sasanian shah, Yazdgerd III, fled east and was assassinated by a local satrap in 651. Far to the west, the Berber commander Tariq ibn Ziyad crossed the Strait of Gibraltar on the 29th of April 711 with a force of Arabs and Berbers, most of them Berbers. After defeating the Visigothic king Roderic at the river Guadalete on the 19th of July 711, Muslim forces swept through Iberia so quickly that by 713 the peninsula was almost entirely under Muslim control.

• 5. The Armies and Their Opponents

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  Arab swords from India were prized as the finest steel available and were the preferred weapons of Muslim fighters; the Arab sword known as the sayfy closely resembled the Byzantine gladius. Swords and spears formed the core of Muslim armaments, with armour of either mail or leather. The Bedouin tribes favoured archery, though contrary to popular belief their archers usually fought on foot rather than on horseback. As the caliphate spread, Muslim forces absorbed tactical influences from the peoples they conquered, including the Turkic peoples of Central Asia and the Persians. British historian David Nicolle called those Turkic peoples the most formidable foes the Muslims encountered. The Jewish Turkic Khazar khanate, based in what is now southern Russia and Ukraine, fielded powerful heavy cavalry, and in 644 an invading Muslim army was almost wiped out by Khazar forces near the Caspian Sea. The heavily armoured Turkic cavalry left a lasting mark on Muslim tactics and weapons; the Turkic peoples, mostly Buddhists at the time of the conquest, later converted to Islam and came to be regarded as the foremost Muslim warriors. The Visigoths in Iberia relied on cavalry and forces raised by the nobility, favouring repeated charges combined with feigned retreats. The Franks were different: their kings required all male subjects to perform three months of military service every year, and those who answered the call had to supply their own weapons and horses. Charles Martel drew on exactly that pool of experienced warriors when he faced the Muslim advance at Tours between the 18th and the 25th of October 732, where his assault on the Muslim camp ended with the death of commander Abd al-Rahman Ibn Abd Allah al-Ghafiqi and the Muslim withdrawal at nightfall.

• 6. Governing the Conquered

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  From the outset, the Rashidun caliphs laid down two foundational rules: Bedouin soldiers would not be allowed to damage agricultural production in conquered territories, and the new leadership would cooperate with local elites. Arab-Muslim armies were settled in segregated garrison towns, including the newly founded Basra, Kufa, and Fustat. Soldiers received a monthly stipend and were prohibited from seizing land. At first, many provinces kept a large degree of autonomy under the terms of their original surrender agreements. The approach to religion followed a similar logic. Before mosques were available in Syria, Muslim forces accepted Christian churches as holy places and shared them with local Christians. Caliph Muawiyah made deliberate efforts to convince those he had conquered that he was not opposed to their religion. Public display of Islam by the state appears to have been absent before the reign of Abd al-Malik from 685 to 705, when Quranic verses and references to Muhammad began appearing on coins and official documents. That shift was driven partly by the desire to unify the Muslim community after the second civil war and rally it against the Byzantine Empire. The Dome of the Rock in Jerusalem was built from 690 to 692 on the site of the Jewish Second Temple, which the Romans had destroyed in 70 AD; the use of Roman and Sasanian symbols of power in the mosque suggests its purpose was partly to celebrate Arab victories over both empires. Mark R. Cohen noted that the jizya poll tax paid by Jews under Islamic rule provided a surer guarantee of protection from hostility than Jews in the Latin West possessed, where rulers could alter their charters and impose arbitrary additional levies.

• 7. Taxation, Conversion, and Fracture

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  Payment of taxes under the new order could reach half of the value of a peasant's produce and carried a mark of social inferiority. Bernard Lewis found evidence suggesting that many subject peoples welcomed the change from Byzantine to Arab rule as a lighter burden; Norman Stillman disagreed, arguing that Christians of the Byzantine Empire and Zoroastrians of Iran faced a considerably heavier load in the immediate aftermath of the conquests. In Egypt, Coptic tax evasion, practised since Roman times, took the form of entering monasteries that were initially exempt, or simply leaving the district of registration. In Iraq, peasants who had fallen behind on taxes converted to Islam and moved to garrison towns to escape collection. The governor of Iraq, al-Hajjaj ibn Yusuf, responded by forcing those converts back to their land and reimposing taxes on them, effectively forbidding conversion to Islam. The tension between religious principle and fiscal reality could not hold indefinitely. The Umayyad caliph Umar II ordered governors to cease collecting taxes from Muslim converts, but his successors obstructed the policy. Some governors introduced additional requirements for conversion, including circumcision and the ability to recite passages from the Quran. Taxation-related grievances among non-Arab Muslims helped fuel the opposition movements that eventually ended the Umayyad dynasty in the Abbasid Revolution. Under the system that finally took hold, kharaj became a land tax applied regardless of the taxpayer's religion, while jizya was reserved for the poll tax on non-Muslim subjects. Julius Wellhausen argued that the poll tax was too small to constitute a serious economic incentive to convert; Daniel Dennett's research showed that the desire to retain social status had greater influence on conversion in the early Islamic period than tax avoidance did.

• 8. Legacy of the Century of Conquest

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  Historian David Nicolle described the series of Islamic conquests of the 7th and 8th centuries as one of the most significant events in world history, one that produced a new civilisation in the Islamicised and Arabised Middle East. Islam, previously confined to Arabia, became a major world religion, while a synthesis of Arab, Byzantine, and Sasanian elements generated new styles of art and architecture across the region. Edward Gibbon, writing in The History of the Decline and Fall of the Roman Empire, observed that under the last of the Umayyads the Arabian empire stretched two hundred days' journey from east to west, from the borders of Tartary and India to the shores of the Atlantic Ocean, and that the language and laws of the Quran were studied with equal devotion at Samarkand and Seville. Arab settlers in Iran largely assimilated into local culture, adopting the Persian language and customs. In garrison towns across Iraq and Egypt, soldiers and administrators of the old order sought their fortunes with the new masters, while labourers and peasants arrived seeking escape from harsh conditions in the countryside. Non-Arab converts were absorbed through a client system adapted from the tribal institution of clientage, through which the protection of the powerful was exchanged for the loyalty of subordinates. The depth of Persian grief over those losses was still alive four centuries later, when the poet Ferdowsi gave voice to the defeated shah Yazdgerd III in his poem Shahnameh, lamenting that uncivilized Arabs had come to make him a Muslim. That literary wound, inflicted long after the armies had moved on, speaks to how completely the conquests had remade the world they passed through.