The Coming of Islam and the Great Transformation

In the opening decades of the seventh century CE, the Sasanians and the Eastern Roman Empire had spent years grinding each other down in a war of attrition. The campaigns of Khosrow Parviz, whose armies had once pushed to the shores of the Mediterranean and the gates of Constantinople, ended in catastrophe with the counterattack of Heraclius and his penetration into the heart of Mesopotamia in 627 CE. The treasury was emptied, the army was exhausted, and the authority of the Kayanian crown crumbled.

After the murder of Khosrow Parviz in 628, the court of Ctesiphon plunged into a whirlpool of strife over the succession; within a short span a number of kings and queens — including two Sasanian women — ascended the throne and were toppled. This instability at the center occurred precisely when a fresh and unified force was taking shape on the Arabian Peninsula: the nascent community of Islam, which, after the death of the Prophet in 632 CE, poured beyond the borders of the Hijaz under the banner of the first caliphs.

This coincidence was no trivial accident — it proved decisive. The Sasanian military organization was still powerful, but its political structure had suffered an internal hemorrhage. Historians regard this moment as the point of fragility of an ancient civilization that had become vulnerable to a newly risen wave.

The first great clashes occurred on the frontiers of Mesopotamia, the land that was the agricultural heart and revenue source of the Sasanians. At the Battle of Qadisiyyah, around 636 CE, the Persian army under the command of Rostam Farrokhzad was defeated in a battle lasting several days. The accounts speak of Persian war elephants, of the dust of the desert, and of the death of the commander; its consequence was the fall of Ctesiphon, the magnificent Sasanian capital, and the plunder of its legendary treasures.

The final blow fell a few years later at the Battle of Nahavand, around 642 CE; a battle the Muslims called the "Conquest of Conquests" (Fath al-Futuh), for with it the concentrated resistance of the imperial army was shattered and the road to the Iranian plateau was thrown open. From then on, the conquest continued as a regional advance, sometimes through separate peace treaties with cities and local nobles.

Yazdegerd III, the last Sasanian king of kings, fled for years from city to city and tried to gather forces, but he was finally killed near Merv in 651 CE by a miller — an obscure death for the last ruler of a dynasty that had reigned for four centuries. With him, the old political order of Iran came to an end, although its society, language, and many of its administrative institutions endured.

The political conquest was swift, but the religious transformation was not. Contrary to a common assumption, the people of Iran did not become Muslims overnight; widespread conversion to Islam was a process that stretched over generations and even centuries. Zoroastrians, Nestorian Christians, Jews, and the followers of other faiths long made up a large portion of the population, and the fire temples in the corners of the plateau still remained lit.

The historian Richard Bulliet, by examining the pattern of Islamic names in the biographies of scholars of the early centuries, has proposed a statistical model according to which the conversion of the Iranians followed a slow and then accelerating trend, and it was probably only around the ninth and tenth centuries CE that Muslims became the majority of the population. It must be emphasized that this is a scholarly, model-based estimate, not a precise count, and Bulliet himself regards it as a cautious approximation that some researchers have questioned in its details.

Meanwhile, the tax system played a key role. Non-Muslim "People of the Book" received protection and relative religious freedom in exchange for paying the jizya — a poll tax. This arrangement created both an economic incentive to convert and, from the viewpoint of the state treasury, a reason why rapid universal conversion was not always desirable.

Even Iranians who embraced Islam were not always reckoned equal to the Arab Muslims. In the Umayyad period, non-Arab new Muslims were called "mawali"; they often had to attach themselves as clients to one of the Arab tribes, and despite their acceptance of the new faith, they sometimes still bore the burden of heavy taxes and social discrimination.

This inequality bred a suppressed anger that became one of the driving engines of political transformation. The discontent of the mawali, especially in Khorasan, provided an important social foundation for a movement that in 750 CE led to the overthrow of the Umayyads and the rise of the Abbasid caliphate; a revolution in which the role of the Iranian-descended commander Abu Muslim Khorasani was prominent.

With the coming to power of the Abbasids and the transfer of the center of the caliphate to Baghdad, near ancient Ctesiphon, the elements of Iranian bureaucracy and culture found a new standing. Iranian-descended vizier families, such as the Barmakids, attained remarkable power and influence, and the Sasanian tradition of statecraft was reproduced in an Islamic mold.

In the shadow of these very tensions, an intellectual and literary movement called "Shu'ubiyya" arose. The Shu'ubis — whose name was taken from a Quranic verse about the equality of "peoples and tribes" — advanced the equality of all Muslims regardless of lineage and stood against the claim of Arab racial superiority.

A more ardent branch of this current went beyond the boundary of equality and turned to praising the ancient heritage of Iran: recalling the glory of the kings of antiquity, the art of statecraft, the wisdom and the manners of the Sasanian court. This debate flowed more in the field of writing and literary polemic than in the arena of politics, but its importance lay in preserving Iranian cultural self-awareness.

Shu'ubiyya showed that one could be at once a devout Muslim and proud of one's Iranian lineage and culture. This very blend — embracing the new faith without forgetting the ancient identity — became one of the enduring features of Iranian Islamic civilization.

Perhaps the most astonishing event of this era is the fate of the Persian language. In lands such as Egypt, Syria, and North Africa, the native languages gradually gave way to Arabic. But Persian was the only major language of a conquered land that not only did not perish, but, after several centuries, rose again as a literary and courtly language.

New Persian — also called "Dari" — was the continuation of the Middle Persian of the Sasanian age, but this time it was written in the Arabic script and had absorbed a great many Arabic words. This language first flourished in the east of Iran, in Khorasan and Transoxiana, as a language of writing and poetry; a place where, far from the center of the caliphate, there was room for its growth.

This return is considered a unique event in the history of conquered lands, and it laid the foundation of one of the richest literary traditions in the world; a tradition that in later centuries gave the world poets such as Rudaki, Ferdowsi, Khayyam, Rumi, Sa'di, and Hafez.

From the ninth century CE, with the loosening of the Abbasid caliphate's direct grip on the east, semi-independent Iranian dynasties emerged; a period that some historians have called the "Iranian Intermezzo." Ya'qub ibn al-Layth al-Saffar, a man risen from the lineage of artisans in Sistan, founded a rule in whose court, according to the accounts, Persian poetry was composed instead of Arabic.

After the Saffarids, the Samanids established a powerful and culture-nurturing state in Transoxiana and Khorasan, whose capital, Bukhara, became one of the great centers of knowledge and letters. The Samanid court supported poets and scholars and elevated New Persian to the official language of the chancery and culture; Rudaki, who has been called the father of Persian poetry, lived in this very court.

These dynasties remained Muslim in religion and, at least outwardly, loyal to the caliphate, but in practice they advanced the revival of the language, the art of statecraft, and the sense of Iran's historical continuity. The combination of religious loyalty to Islam and Iranian cultural pride came to maturity in this period.

Concurrent with this cultural resurgence, the Islamic world witnessed a remarkable scientific flowering that is called the "Islamic Golden Age," and the Iranians stood at its center. The important point is that most of these scholars wrote their scientific works in Arabic, because Arabic in that age was the common language of knowledge throughout the Islamic realm — precisely the role that Latin held in medieval Europe.

Muhammad ibn Musa al-Khwarizmi in Baghdad laid the foundations of algebra; the word "algorithm" in European languages is derived from his name, and the word "algebra" from the title of his book. Muhammad ibn Zakariya al-Razi, the great physician and chemist, wrote the first precise clinical descriptions of diseases such as smallpox and measles. Abu Rayhan al-Biruni wrote across an astonishing range, from astronomy and mathematics to anthropology and the measurement of the earth's radius.

Among them, Abu Ali Sina, known in the West as Avicenna, wrote his medical masterpiece, the "Canon," which for centuries was a textbook in the universities of East and West; his philosophical work, the "Healing" (Shifa), also blended Aristotelian thought with Islamic philosophy. These achievements were a shared heritage for the Islamic world, but the Iranian share in them is so prominent that it cannot be overlooked.

The peak of this conscious effort to safeguard the Iranian identity was crystallized in the "Shahnameh" of Abolqasem Ferdowsi of Tus; an epic poem of about fifty thousand verses whose composition was completed near the year 1010 CE. In an age when Arabic was the language of science and religion, Ferdowsi consciously sang the tale of the kings and heroes of Iran, from creation to the fall of the Sasanians, in the Persian tongue and with the fewest foreign words.

The Shahnameh is not merely a collection of legend and battle; it is a deliberate effort to keep alive the collective memory of a nation in the mold of its own language. Many have considered this work a fundamental factor in the survival of the language and national self-awareness of the Iranians.

The story of Ferdowsi's relationship with Sultan Mahmud of Ghazni — that the poet toiled for years and in the end received a paltry and belated reward and died embittered — is one of the most famous narratives of Persian literature. Nevertheless, a large part of this account is semi-legendary and was elaborated in later sources; today's researchers doubt the accuracy of much of it, although its core — the poet's connection with the Ghaznavid court — is acceptable.

What happened over these few centuries cannot be understood in the simple frame of "destruction" or "surrender." The military conquest overthrew the Sasanian political order, but Iranian society neither vanished nor was wholly dissolved into the conquerors. Instead, a two-way process occurred: the Iranians embraced Islam and gave it shape, and gave new birth to their ancient heritage in a fresh mold.

The result was a civilization Iranian and Islamic at once; a land in which the verses of the Quran and the verses of the Shahnameh, science written in Arabic and poetry composed in Persian, lived side by side. This dual and intertwined identity became the foundation of the Iran of later centuries and has endured to our own day.

From defeat, continuity was born; and from the encounter of two cultures, a new creation arose — this is perhaps the most telling interpretation of the "Great Transformation."