Iran enjoys one of the richest historical lineages of any modern state stretching back several thousand years. This history can be broadly divided into three epochs: the pre-Islamic ancient period (c559 BC to 651 AD); the Islamic era (651 AD to 1800 AD); and the modern era, defined by its encounter with Western modernity from around 1800.


The pre-Islamic ancient period

‘Iranian’ history proper begins with the migration of the Iranian tribes from Central Asia onto what is now known as the Iranian plateau in the 2nd millennium BC. But organised human settlement developed much earlier and Elamite civilisation in south western Iran – southern Iraq today – emerged in the third millennium. By the 1st millennium BC, two distinct Iranian states emerged in the form of the Medes and Persians and their emphatic entrance onto the world stage began with the accession of Cyrus II in 559 BC.

Cyrus II
Cyrus II, aka Cyrus the Great. (Photo by Bettmann via Getty Images)

The Achaemenid Persian Empire grew to become the largest contiguous land empire then known to man, impressing both friend and foe alike with its relatively benign administration drawing on religious ideas that would later be associated with Zoroastrianism, the pre-Islamic religion of Iran identified with the mantra “good words, good thoughts and good deeds”. It looms large in the Western imagination because of its failed attempts to conquer the Greek states and its subsequent defeat at the hands of Alexander the Great some 150 years later in the 330s BC. Hellenized rule under Alexander’s successors – the Seleucids – lasted a century until the arrival of a new Iranian dynasty from the east, the Parthians.

The Parthian Empire

The Parthian Empire reshaped Iranian history by importing myths and legends from the east and supplanting the Achaemenids in popular memory. This decentralised kingdom – in which the king was first among equals; a king over other kings, if you will – made up for its fractiousness with longevity (it is the longest lived of all Iranian dynasties) and proved a serious foe to the emergent Roman empire, inflicting upon it one of its greatest defeats. This was at the plains of Carrhae in 53 BC, where the Roman commander Crassus (famous for his defeat of Spartacus) was decisively defeated by a smaller Parthian force largely composed of horse archers, losing some two-thirds of his legions and several ‘eagles’ [Romans Standards]. After 500 years, in 224 AD the Parthians were in turn overthrown by another dynasty, this time from the heartlands of Persia itself, the Sasanians.

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The Sasanians were undoubtedly the heirs of the Parthians but their empire was more centralised and the ‘king of kings’ was more than a first among equals. Administration was consolidated and Zoroastrianism was promoted as an official and increasingly well-defined creed. In time Sasanian kings, most notably Khusrau II, would come to symbolise all that was good about pre-Islamic Iran and its administration.

Like their predecessors, the Sasanians proved formidable opponents to the Roman and then Byzantine Empires, engaging in a cycle of conflicts which ultimately exhausted both empires and made them vulnerable to hitherto unforeseen challenges.

The Islamic era

In the 7th century a new power emerged from the Arabian Peninsula – Islam. Defeating the Byzantines, the Muslim Arab armies eventually conquered and absorbed the Sasanian empire into the new Caliphate. The Iranian empire was too large a morsel for the Caliphate to fully digest, with the result that Iranian ideas on the nature and practice of ‘just’ government and culture began to shape the way in which the Caliphate developed.

Islam transformed the Iranian world view, but the political and religious culture of the Islamic world was in turn shaped by the profound legacy of ancient Iran and many of the leading administrative and scientific minds of the classical Islamic age including the polymath Ibn Sina (Avicenna) and the famous vizierial (ministerial) family of the Barmakids, emanated from the Iranian world.

Indeed the emphatic influence of the Iranian world was made clear with the emergence of the Abbasid Caliphate in 749 AD and the transfer of the capital from Damascus to the newly founded city of Baghdad (around 762 AD), not far from the old Sasanian capital. This Iranian turn was exemplified by the development of the ‘new’ Persian language, now empowered with the adoption of the Arabic alphabet to become the lingua franca of the eastern Islamic world, and in time one of the great literary languages of the world.

The Islamic era would witness another profound development in the history of Iran with the entrance of the Turkic peoples from central Asia from the 11th century, but most consequentially with the eruption of the Mongols (nomadic warriors from the steppes of inner Asia) in the 13th century. The Mongol conquest facilitated the migration of the Turkic tribes onto the plateau – forcing a knock-on migration of Iranians onto the Anatolian plateau – fundamentally altering the political economy of the country from one which was largely sedentary to one with a significant nomadic component, especially in the northern parts of the country.

Moreover, Mongol and Turkic words (such as ‘Khan’) feed into the Persian language adding further dimension to the vocabulary of an already rich and diverse language. In economic terms, however, the wave of nomadic invasions beginning with the Mongols and culminating in the devastation wrought by Tamerlane in the 14th century, resulted in widespread economic dislocation. It was to be many years before the economic lifeblood returned in any meaningful sense.

Mongols laying siege to Baghdad in 1258
A Persian manuscript depicting the Mongols laying siege to Baghdad in 1258. (Photo by DeAgostini/Getty Images)

At the same time, taking the long view, the Mongol conquests ensured that ‘Iran’ as a distinct political entity re-emerged after centuries of seclusion within the wider Islamic world. It says something of the cultural confidence and richness of Iranian civilisation that it was able to re-form as a distinct state in its own right and by the 16th century a new dynasty was to emerge which would add further layers to this distinctiveness.

Iran had been absorbed into the Caliphate but had retained its own language and culture such that it began to influence the shape and direction of travel of the Islamic world. Even the Turkic nomads would in turn come to appreciate the cultural powerhouse that Iran and the Persian world represented, adopting and adapting many of its cultural attributes including the Persian language. With the rise of the Safavids in the 16th century this cultural confidence was given political form once again and in order to consolidate their position the Safavids imposed the minority branch of Islam, Shiism, as the new state religion from 1501.


Followed by about 10 per cent of all Muslims today, Shi’ism is the minority branch of Islam. It originates in a dispute over the succession to the Prophet Mohammad but has developed a distinct approach towards scriptural interpretation which lends weight to the scriptural authority of its ‘Imams’ descended from the Prophet’s cousin and son-in-law, the first Imam, Ali (from which the term ‘Shi’a’ – party of Ali, derives), and in the absence of the Imams, those religious scholars who are held in high esteem by the community.

There are several Shia sects, the two most prominent being the Twelvers and Seveners (or Ismailis), relating to the number of hereditary Imams recognised. In 1501 the Safavids introduced Twelver Shiism into Iran where it remains the state religion. The Twelfth Imam, Mahdi, is considered to have gone into Occultation in the 9th century, remaining ‘Hidden’ from his followers pending his reappearance at an unspecified time when he will inaugurate an era of justice. During his Occultation, senior religious scholars, known today as ‘Ayatollahs’, have made various claims to his authority.

This proved to be something of a double-edged sword. The adoption of Shiism helped distinguish the Iranian state from its Ottoman rival to the West. But it also served to hinder political ties with the Persianate world of the east. Nonetheless, over two centuries the Safavids oversaw a flourishing of Iranian civilisation, most notably under Shah Abbas I (1587–1629), the only king after the Islamic conquest to be known as ‘the Great’. Indeed, just as Iranians ascribed all pre-Islamic achievements to the reign of Khusrau I, so too was Shah Abbas credited with all and any achievements during the Islamic period.

It was during this period that the first systematic contacts were made between Iran and Europe, as European merchants came to establish commercial, and in some cases, political, ties.

Shah Abbas I 'the Great'
Persian cavalry soldiers led by Shah Abbas I 'the Great' fighting against the Turks. (Photo by PHAS/Universal Images Group via Getty Images)

Modern challenges

It is to Iran’s misfortune that the period of the most dramatic growth in European power and western civilisation in the 18th century coincided with a period of political turmoil within Iran itself. The traumatic fall of the Safavid dynasty in 1722 resulted in decades of warfare as first Iran re-emerged empowered under the leadership of Nader Shah (1736–47), only to once again descend into turmoil following his death.

As a little-known footnote in history, it was Nader Shah’s invasion and defeat of the Mughal Empire in 1739 that paradoxically opened up India to European penetration in the 18th century. And by the time Iran emerged from its turmoil by the end of the 18th century it faced a whole new challenge in the Russian and British empires. These were not just political threats but ideological ones with self-confident European powers who were not in awe of Iranian civilisation – on the contrary, they regarded the political economy of the Iranian state to be archaic and dependent on the authority and despotic power of its kings.

European power approached the world with new ideas about the organisation of the state, the rule of law and constitutionalism, all of which were alien to the Iranian world but which gained traction among a group of intellectuals who regarded the salvation of Iran in the adoption of these new and innovative forms of political and economic organisation. Iranians, so used to educating the world, found themselves in the reluctant position of being the student. Throughout the 19th century Iranian intellectuals and activists sought to promote reform but were faced with the objections of reactionary elements within Iran (most notably a monarchy reluctant to concede power) and with the ambivalence of imperial European powers ultimately more anxious to maintain the balance of power.

Eventually, at the turn of the 20th century, in 1906, the first of Iran’s revolutions – the Constitutional Revolution – established a parliamentary system on the British model, complete with a constitution and separation of powers. It was a seminal moment that altered the political landscape of the country. But its ambitions were high and its promise remained unfulfilled as a new dynasty – the Pahlavis (1925–79) – sought to impose revolution from above.

With the emergence of the Pahlavis in 1925 the revolutionary impetus of 1906 was adopted with some vigour by the new monarch supported initially by many of the intellectuals of the period who were anxious to see the creation of a modern state that would enable their many reforms to education and the judicial system to be realised. Reza Shah’s rule oversaw a transformation of the country but the reforms he oversaw were only partially fulfilled, with the growth in the power of the state not being matched by a growth in civil society and civic rights.

Overthrown following an Allied occupation (1941–46) in the turmoil of the Second World War, he was succeeded by his young son Mohammad Reza Shah (1941–79) who for the first period of his reign had to contend with growing factionalism as well as the continued interference of foreign powers. The crisis over the continued Soviet occupation of Azerbaijan was resolved in 1946, but a more serious crisis over Iran’s oil industry resulted in an Anglo-American orchestrated coup to overthrow the nationalist prime minister Dr Mohammad Mosaddeq who had encouraged the Shah to reign rather than rule. As with the revolution of 1906, the coup of 1953 was to cast a long shadow over Iranian politics and the Shah struggled to emerge from it.

Rioters in Tehran, 1953
Rioters run in the streets of Tehran during the Anglo-American organised coup against Mosaddeq, August 1953. (Photo by AFP via Getty Images)

Royal autocracy and the ‘Islamic’ revolution

In the 1960s the Shah felt strong enough to launch a ‘White’ revolution of his own, further transforming the socio-economic landscape of the country but failing to match these dramatic changes with a measure of political reform. Indeed, far from democratising, the 1970s witnessed a retrenchment of royal autocracy. Political stagnation with social and economic change proved to be a combustible combination to which was added a religious revival centred on the figure of Ayatollah Khomeini. By 1978 the Shah, faced with opposition from nationalists, the left and the religious groups, found himself no longer master of his political domain, increasingly at a loss as to how to react to the groundswell of discontent.

He went into exile in January 1979. Two weeks later Ayatollah Khomeini returned to the adulation of the crowds (pictured above) and in short order the monarchy was replaced by an Islamic Republic. But this new ‘Islamic’ revolution proved no more successful in reconciling Iran’s traditions with the challenges of modernity. The seizure of the US Embassy in November 1979 and the start of a protracted war with Iraq in 1980, which lasted to 1988, both scarred and defined the emergent Islamic Republic. Rampant factionalism was not expunged by the violent suppression of the Left, and the Islamic Republic has been characterised by fierce debates over the nature and character of the state dividing between those who favour the republican institutions and those who seek the establishment of an Islamic government.

The dominance of the ‘Islamists’ and the growing autocracy of the ‘supreme leader’ indicate that the problems of 1906 remain unresolved and that 1979 simply witnessed the ‘crown’ being replaced by the ‘turban’.

A brief history of Iran – a timeline

c2700 BC Emergence of Elamite civilisation
c1500 BC Iranian migrations from Central Asia
c1000 BC Zoroaster ministers in eastern Iran
539 BC Conquest of Babylon, liberation of the Jews
490 BC First invasion of Greece – battle of Marathon
480 BC Second invasion of Greece – battle of Salamis
331 BC Conquest of Persian Empire by Alexander the Great
312–247 BC Seleucid Empire
247 BC Rise of the Parthian Empire
53 BC Romans defeated at the battle of Carrhae
224 AD Rise of the Sasanian Empire
651 AD Collapse and absorption of the Sasanian Empire to the Arab Muslims
749 AD Establishment of Abbasid Caliphate, start of Persian renaissance
1010 Ferdowsi completes the Shahnameh
1040 Rise of the Saljuq dynasty
1219 First Mongol invasion under Chinggis Khan
1258 Mongol sack of Baghdad
1370–1405 Rule of Tamerlane
1501 Rise of the Safavid Empire, establishment of Shiism
1722 Collapse of the Safavid Empire to Afghan invasion
1736–47 Rule of Nader Shah
1785 Emergence of the Qajar dynasty
1804–13 First Russo-Persian War – Treaty of Golestan
1826–28 Second Russo-Persian War – Treaty of Turkmenchai
1856–67 Anglo-Persian war – Treaty of Paris
1901 Oil concession awarded to Britain
1906 Constitutional Revolution
1907 Anglo-Russian Convention
1919 Anglo-Persian Agreement
1921 February Coup and rise of Reza Khan
1925 Establishment of the Pahlavi dynasty
1941–46 Allied occupation of Iran
1946 Azerbaijani Crisis
1951–53 Oil Nationalisation Crisis
1953 Anglo-American organised coup against Mosaddeq
1963 Launch of White Revolution
1979 Islamic Revolution overthrows monarchy
1980–88 Iran-Iraq War
1989 Death of Ayatollah Khomeini


Ali M Ansari is a professor of history at the University of St Andrews specialising in the history of Iran and author of several books including Iran: A Very Short Introduction (Oxford University Press, 2014); The Politics of Nationalism in Modern Iran (Cambridge University Press, 2012); and Iran, Islam and Democracy: The Politics of Managing Change 3rd Ed. (Gingko/Chatham House, 2019)