Muslim conquest of Persia
The Muslim conquest of Persia or Arab conquest of Iran occurred between 633 and 651, when the Rashidun Caliphate conquered the Sasanian Empire as part of the early Muslim conquests, which began under Muhammad in 622.
Historical context
While Arabia was witnessing the rise of Islam in the 7th century, Persia was struggling with unprecedented political, economic and social issues as well as military weakness; the Sasanian army had greatly exhausted itself in the Byzantine–Sasanian War of 602–628.Following the execution of Sasanian shah Khosrow II in 628, Persia's internal political stability began to deteriorate rapidly, leading to ten new royal claimants being enthroned within the next four years. Shortly afterwards, Persia was further devastated by the Sasanian Interregnum, a large-scale civil war that began in 628 and resulted in the government's decentralization by 632.
Amidst Persia's turmoil, the first Rashidun invasion of Sasanian territory took place in 633, when the Rashidun army conquered parts of Asoristan, which was the Sasanians' political and economic centre in Mesopotamia. Later, the regional Rashidun army commander Khalid ibn al-Walid was transferred to oversee the Muslim conquest of the Levant, and as the Rashidun army became increasingly focused on the Byzantine Empire, the newly conquered Mesopotamian territories were retaken by the Sasanian army.
The second Rashidun invasion began in 636, under Sa'd ibn Abi Waqqas, when a decisive victory at the Battle of al-Qadisiyyah, put a permanent end to any Sasanian control west of modern-day Iran. For the next six years, the Zagros Mountains, a natural barrier, marked the political boundary between the Rashidun Caliphate and the Sasanian Empire. In 642, Umar ibn al-Khattab, eight years into his reign as Islam's second caliph, ordered a full-scale invasion of the rest of the Sasanian Empire. Directing the war from the city of Medina in Arabia, Umar's quick conquest of Persia in a series of coordinated and multi-pronged attacks became his greatest triumph, contributing to his reputation as a great military and political strategist. In 644, however, he was assassinated by the Persian craftsman Abu Lu'lu'a Firuz, who had been captured by Rashidun troops and brought to Arabia as a slave.
Some Iranian historians have defended their forefathers by using Arab sources to illustrate that "contrary to the claims of some historians, Iranians, in fact, fought long and hard against the invading Arabs." By 651, most of the urban centres in Iranian lands, with the notable exception of the provinces along the Caspian Sea such as Tabaristan and Transoxiana, had come under Muslim domination. Many localities fought against the invaders; although the Rashidun army had established hegemony over most of the country, many cities rose in rebellion by killing their Arab governors or attacking their garrisons. Eventually, military reinforcements quashed the Iranian insurgencies and imposed complete control. The Islamization of Iran was gradual and incentivized in various ways over a period of centuries, though some Iranians never converted and there is evidence of Zoroastrian scriptures and all other pre-Islamic being burnt and Zoroastrian priests being executed, particularly in areas that were centers of resistance. Islam had become Iran's predominant religion by the Late Middle Ages; the majority of Iranians were Sunni Muslims until the Safavids forcefully converted Iran to Shia Islam in the 16th century.
This was the first time since the collapse of the Neo-Babylonian Empire in 539 BC at the Battle of Opis, that Mesopotamia was ruled again by Semitic-speaking people. This was after centuries of Iranian rule under the Achaemenid, Parthian and Sasanian empires, as well as the Greco-Roman Macedonian, Seleucid, and Roman empires.
This event led to the decline of Zoroastrianism, which had been the official religion of Persia since the time of the Achaemenid Empire, circa 550 BC. The persecution of Zoroastrians by the early Muslims during and after this conflict prompted many of them to flee eastward to India, where they were taken as refugees by various kings.
Historiography and recent scholarship
When Western academics first investigated the Muslim conquest of Persia, they relied solely on the accounts of the Armenian Christian bishop Sebeos, and accounts in Arabic written some time after the events they describe. The most significant work was probably that of Arthur Christensen, and his L’Iran sous les Sassanides, published in Copenhagen and Paris in 1944.Recent scholarship has begun to question the traditional narrative: Parvaneh Pourshariati, in her Decline and Fall of the Sasanian Empire: The Sasanian-Parthian Confederacy and the Arab Conquest of Iran, published in 2008, provides both a detailed overview of the problematic nature of trying to establish exactly what happened, and a great deal of original research that questions fundamental facts of the traditional narrative, including the timeline and specific dates.
Pourshariati's central thesis is that contrary to what was commonly assumed, the Sassanian Empire was highly decentralized, and was in fact a "confederation" with the Parthians, who themselves retained a high level of independence. Despite their recent victories over the Byzantine Empire, the Parthians unexpectedly withdrew from the confederation, and the Sassanians were thus ill-prepared and ill-equipped to mount an effective and cohesive defense against the Muslim armies. Moreover, the powerful northern and eastern Parthian families, the kust-i khwarasan and kust-i adurbadagan, withdrew to their respective strongholds and made peace with the Arabs, refusing to fight alongside the Sassanians.
Another important theme of Pourshariati's study is a re-evaluation of the traditional timeline. Pourshariati argues that the Arab conquest of Mesopotamia "took place, not, as has been conventionally believed, in the years 632–634, after the accession of the last Sasanian king Yazdgerd III to power, but in the period from 628 to 632." An important consequence of this change in timeline means that the Arab conquest started precisely when the Sassanians and Parthians were engaged in internecine warfare over succession to the Sassanian throne.
Sasanian Empire before the conquest
Since the 1st century BC, the border between the Roman and Parthian empires had been the Euphrates River. The border was constantly contested. Most battles, and thus most fortifications, were concentrated in the hilly regions of the north, as the vast Arabian or Syrian Desert separated the rival empires in the south. The only dangers expected from the south were occasional raids by nomadic Arab tribesmen. Both empires therefore allied themselves with small, semi-independent Arab principalities, which served as buffer states and protected Byzantium and Persia from Bedouin attacks. The Byzantine clients were the Ghassanids; the Persian clients were the Lakhmids. The Ghassanids and Lakhmids feuded constantly, which kept them occupied, but that did not greatly affect the Byzantines or the Persians. In the 6th and 7th centuries, various factors destroyed the balance of power that had held for so many centuries.The conflict with the Byzantines greatly contributed to its weakness, by draining Sassanid resources, leaving it a prime target for the Muslims.
Social problems
Sasanian society was divided into four classes: priests, warriors, secretaries, and commoners. The latter formed the bulk of the population, served as its sole tax base, and remained its poorest class.At the climax of Khosrow II's ambitious Byzantine territory conquests in the Levant and much of Asia Minor, taxes rose dramatically, and most people could not pay. Years of Sassanid-Byzantine wars had ruined trade routes and industry, the population's main income sources. The existing Sassanid administrative structure proved inadequate when faced with the combined demands of a suddenly expanded empire, economy, and population. Rapid turnover of rulers and increasing provincial landholder power further diminished the Sasanians. Over a period of fourteen years and twelve successive kings, the Sassanid Empire weakened considerably, and the power of the central authority passed into the hands of its generals. Even when a strong king emerged following a series of coups, the Sassanids never completely recovered.
Events
Revolt of the Arab client states (602)
The Byzantine clients, the Arab Ghassanids, converted to the Monophysite form of Christianity, which was regarded as heretical by the established Byzantine Eastern Orthodox Church. The Byzantines attempted to suppress the heresy, alienating the Ghassanids and sparking rebellions on their desert frontiers. The Lakhmids also revolted against the Persian king Khusrau II. Nu'man III, the first Christian Lakhmid king, was deposed and killed by Khusrau II in 602, because of his attempt to throw off Persian suzerainty. After Khusrau's assassination in 628, the Persian Empire fractured and the Lakhmids were effectively semi-independent. It is now widely believed that the annexation of the Lakhmid kingdom was one of the main factors behind the fall of the Sasanian Empire and the subsequent Islamic conquest of Persia, as the Lakhmids agreed to act as spies for the Muslims after being defeated in the Battle of Hira by Khalid ibn al-Walid.Byzantine–Sassanid War (602–628)
The Persian ruler Khosrau II defeated a dangerous rebellion within his own empire, Bahram Chobin's rebellion. He then turned his focus to his traditional Byzantine enemies, leading to the Byzantine-Sassanid War of 602–628. For a few years, he succeeded. From 612 to 622, he extended the Persian borders almost to the same extent that they were under the Achaemenid dynasty, capturing Western states as far as Egypt, Palestine, and more.The Byzantines regrouped and pushed back in 622 under Heraclius. Khosrau was defeated at the Battle of Nineveh in 627, and the Byzantines recaptured all of Syria and penetrated far into the Persian provinces of Mesopotamia. In 629, Khosrau's general Shahrbaraz agreed to peace, and the border between the two empires was once again the same as it had been in 602.