The early Muslim conquests, or the early Islamic conquests (Arabic: الْفُتُوحَاتُ الإسْلَامِيَّة, romanized: al-Futūḥāt al-ʾIslāmiyya), also known as the Arab conquests, were a series of wars initiated by the Islamic prophet Muhammad, and continued by the early Muslims. In 622, he established the first Islamic state in Medina, with Muslim armies expanding rapidly out of Arabia under the succeeding Rashidun Caliphate and then the Umayyad Caliphate, culminating in Muslim rule being established throughout most of the Middle East and North Africa, parts of South Asia and Central Asia, and parts of Southern Europe over the following century. According to the Scottish historian James Buchan: "In speed and extent, the first Arab conquests were matched only by those of Alexander the Great, and they were more lasting." At the height of the expansion, Muslim-ruled territory under the Caliphates is estimated to have covered 13,000,000 square kilometres (5,000,000 sq mi), stretching from the Indian subcontinent (at Sind) in the east to the Iberian Peninsula (up to Septimania) in the west.
Among other socio-political changes, the early Muslim conquests caused a rupture in the status quo dominated by the Sasanian Empire in the east and the Byzantine Empire in the west; Muslim armies overran the Sasanians and confined the Byzantines, who were left with part of Anatolia and Southeastern Europe. Detailed explanations for the success of the Muslim campaigns have been difficult to discover, largely because only fragmentary sources have survived from the period. American scholar Fred Donner suggests that Muhammad's establishment of the first Islamic state coupled with ideological coherence and mobilization constituted the main factor that propelled his community to successfully establish one of the largest empires in history. Most historians also agree that, as another primary factor that favoured the Muslim war effort, the Sasanians and the Byzantines were rendered militarily and economically exhausted from decades of warfare against each other, with the Sasanian civil war of 628–632 further accelerating political collapse.
It is also believed that Jews and some Christians in both Sasanian and Byzantine territory may have been dissatisfied with the state of the two empires and either welcomed or were indifferent to the invading Muslim troops. However, Arab Christian confederations such as the Ghassanids initially allied themselves with the Byzantines. There were also instances of working alliances being established between the Sasanians and the Byzantines in spite of their prior hostilities, such as when they combined forces against the Rashidun army during the Battle of Firaz in 633/634. A significant portion of the lands that the Byzantines lost to Muslim offensives in Syria and in Egypt had been taken back from Sasanian occupation just a few years earlier.
Background
Pre-Islamic Arabia
Arabia was a region that hosted several cultures, some urban and others nomadic Bedouin. Arabian society was divided along tribal and clan lines, with the most important divisions being between the "southern" and "northern" tribal associations. Both the Byzantine and Sasanian empires competed for influence in Arabia by sponsoring clients; in turn, Arabian tribes sought the patronage of the two rival empires to bolster their own ambitions. The Lakhmid kingdom, which covered parts of what is now southern Iraq and northern Saudi Arabia was a client of Persia, and in 602 the Persians deposed the Lakhmids to take over the defense of the southern frontier. This left the Persians exposed and overextended, helping to set the stage for the collapse of the Persian Empire later that century.
Southern Arabia had, for thousands of years, been a wealthy region at the center of an international trading network, prominently including the spice trade, linking Eurasia, Africa, Europe, the Middle East, India and even from as far away as China. In turn, the Yemeni were skilled sailors, travelling up the Red Sea to Egypt and across the Indian Ocean to India and down the east African coast. Inland, the valleys of Yemen had been cultivated by a system of irrigation that had been set back when the Marib Dam was destroyed by an earthquake in about 450 AD. Frankincense and myrrh had been greatly valued in the Mediterranean region, being used in religious ceremonies. However, the conversion of the Mediterranean world to Christianity had significantly reduced the demand for these commodities, causing a major economic slump in southern Arabia which helped to create the impression that Arabia was a backward region.
Byzantine–Sasanian Wars
The prolonged and escalating Byzantine–Sasanian wars of the 6th and 7th centuries and the recurring outbreaks of bubonic plague (Plague of Justinian) left both empires exhausted and weakened in the face of the sudden emergence and expansion of the Arabs. The last of these wars ended with victory for the Byzantines: Emperor Heraclius regained all lost territories and restored the True Cross to Jerusalem in 629. The war against Zoroastrian Persia, whose people revered fire as a symbol of divine power, had been portrayed by Heraclius as a holy war in defense of the Christian faith and the Wood of the Holy Cross, as splinters of wood said to be from the True Cross were known, had been used to inspire Christian fighting zeal. The idea of a holy war against the "fire worshipers", as the Christians called the Zoroastrians, had aroused much enthusiasm, leading to an all-out effort to defeat the Sassanid Persians.
Nevertheless, neither empire was given any chance to recover, as within a few years they were overrun by the advances of the Arabs (newly united by Islam), which, according to James Howard-Johnston, "can only be likened to a human tsunami". According to George Liska, the "unnecessarily prolonged Byzantine–Persian conflict opened the way for Islam".
Conquest of the Arabian Peninsula
According to Islamic tradition, Muhammad, a merchant from Mecca, began receiving revelations from God through the archangel Gabriel, emphasizing the worship of one God and social justice. After entering conflict with and persecution by the elite of Mecca, he migrated to the city of Yathrib (Medina), where he established the first Islamic state. By 630, he and his followers returned to and conquered Mecca. Already, late in Muhammad's life, the first Muslim-Byzantine skirmishes took place, such as during the Battle of Mu'tah in 629. In 632, Muhammad died and was succeeded by the first caliph, Abu Bakr, who united the Arabian Peninsula after the Ridda Wars.
Many of the material conditions of the pre-Islamic Arabian Peninsula and ancient Near East enabled the success of the conquests. First, over the course of the sixth and early seventh century, all major state and military powers of the Arabian Peninsula dissolved, leaving behind a power vacuum. For the Byzantine and Persian empires, they each respectively projected power into the Arabian peninsula through alliances with two major Arab kingdoms, the Ghassanids and the Lakhmids. The main function of these kingdoms, for the empires, was to serve as buffer states protecting the empires from military incursions by Arab nomads, and to wage proxy wars against each other. However, in the late sixth century, both empires sought direct control over their borders with the Peninsula, and deposed their respective client kingdoms in the process, a few years before the start of the Byzantine-Sasanian wars. The only other principal military force on the Peninsula, the Himyarite Kingdom of South Arabia, had already dissolved by the middle of the sixth century, due to a combination of military, climactic, and economic factors.
By the mid-630s, in the years immediately before the invasion of the Near East, the now-united Arabian Peninsula had achieved its greatest power relative to that of the Near Eastern forces. The Byzantine and Persian powers were unusually weak at this time, as a consequence of a catastrophic and full-fledged thirty-year war between the two that had depleted their manpower, resources, and morale. By contrast, the Arabian Peninsula had been united under a singular leadership for the first time. Accordingly, "the military energy of the Arabs, hitherto dissipated in low-level conflicts between tribal groups, could now be redirected to the conquest of the vastly richer lands beyond the Arabian borders, catching the empires at a time when they were least able to parry this threat. In short, if the Arabs were ever to conquer themselves an empire, this was when it had to happen."
Historians have compared the early Muslim conquests to other conquests. According to Robert Hoyland, lightning-speed conquests over large regions have historically been achieved by nomadic groups found beyond established civilizations, like the Mongols. McCants compares the Arab conquests to earlier conquests of the Near East, first by Alexander the Great of Macedon, and then by the Romans. Between the Macedonians, the early Romans, and the early Arabs, McCants says: "All three conquering peoples hailed from the margins of the Near East, and their conquests united separate, complex societies with ancient native traditions of learning and legitimation distinct from those of the conquerors and one another". In the decades before the Arab conquests by Muhammad and his successors, most of the Arabian Peninsula was previously united by the conquests of the South Arabian king Abraha, including almost all of Arabia Deserta, with multiple campaigns being launched into the Hejaz (which succeeded in conquering Medina) and even into southern Iraq. Abraha's power at this time is further reflected by his hosting of an international conference which included ambassadors being sent for attendance from across the Byzantine, Persian, Ghassanid, and Lakhmid powers. In the 600s and 610s, the region of the Near East north of the Arabian Peninsula, was already under a constant fear and threat of Arab invasion. Already in the mid-6th century, the Romans had to sign a peace treaty that involved paying tribute to Arab kingdoms so as not to be attacked by them. The Battle of Dhi Qar, taking place between 604 and 611, already resulted in an Arab tribal confederation, the Banu Bakr, defeating the Sasanians in southern Iraq and reducing Sasanian control over Eastern Arabia.
Armies
Arab
In Arabia, swords from India were greatly esteemed as being made of the finest steel and were the favorite weapons of the Mujahideen. The Arab sword known as the sayfy closely resembled the Byzantine gladius. Swords and spears were the major weapons of the Muslims, and armour was either mail or leather.
In northern Arabia, Byzantine influence predominated; in eastern Arabia, Persian influence predominated; and in Yemen, Indian influence was felt. As the caliphate spread, the Muslims were influenced by the peoples they conquered—the Turkic peoples in Central Asia, the Persians, and the Byzantines in Syria. The Bedouin tribes of Arabia favored archery, though contrary to popular belief Bedouin archers usually fought on foot instead of horseback. The Arabs usually fought defensive battles with their archers placed on both flanks.
By the Umayyad period, the caliphate had a standing army, including the elite Ahl al-Sham ("people of Syria"), raised from the Arabs who settled in Syria. The caliphate was divided into jund, or regional armies, stationed in the provinces being made of mostly Arab tribes who were paid monthly by the Diwan al-Jaysh (War Ministry).
Byzantine
The infantry of the Byzantine army continued to be recruited from within the Byzantine Empire, but much of the cavalry were either recruited from "martial" peoples in the Balkans or in Asia Minor or alternatively were Germanic mercenaries. Most of the Byzantine troops in Syria were indigenae (local), and it seems that at the time of the Muslim conquest, the Byzantine forces in Syria were Arabs. In response to the loss of Syria, the Byzantines developed the phylarch system of using Armenian and Arab Christian auxiliaries living on the frontier to provide a "shield" to counter raiding by the Muslims into the empire. Overall, the Byzantine army remained a small but professional force of foederati. Unlike the foederati who were sent where they were needed, the stradioti lived in the frontier provinces.
Persian
During the last decades of the Sasanian empire, the frequent use of royal titles by Persian governors in Central Asia, especially in what is now Afghanistan, indicates a weakening of the power of the Shahanshah (King of Kings), suggesting the empire was already breaking down at the time of the Muslim conquest. Persian society was rigidly divided into castes with the nobility being of supposed "Aryan" descent, and this division of Persian society along caste lines was reflected in the military. The azatan aristocracy provided the cavalry, the paighan infantry came from the peasantry and most of the greater Persian nobility had slave soldiers, this last being based on the Persian example. Much of the Persian army consisted of tribal mercenaries recruited from the plains south of the Caspian Sea and from what is now Afghanistan. The Persian tactics were cavalry based with the Persian forces usually divided into a center, based upon a hill, and two wings of cavalry on either side.
Ethiopian
Little is known about the military forces of the Christian state of Ethiopia other than that they were divided into sarawit professional troops and the ehzab auxiliaries. The Ethiopians made much use of camels and elephants.
Berber
The Berbers of North Africa had often served as foederati (auxiliaries) in the Byzantine army. Berber forces were based around the horse and camel but seemed to have been hampered by a lack of weapons or protection, with both Byzantine and Arab sources mentioning the Berbers lacked armour and helmets. The Berbers went to war with their entire communities, and the presence of women and children both slowed down the Berber armies and tied down Berber tribesmen who tried to protect their families.
Turkic
The British historian David Nicolle called the Turkic peoples of Central Asia the "most formidable foes" faced by the Muslims. The Khazar Khaganate, based in what is now southern Russia and Ukraine, had a powerful heavy cavalry. Central Asia was divided into five khanates whose khans variously recognized the Shahs of Iran or the Emperors of China as their overlords.