I recommend Michael Axworthy’s A History of Iran: Empire of the Mind because there are very few books aimed at the general audience that survey the history of Persia from the ancient period down to the modern one with some balance. Often the Iranian Revolution and contemporary events are given too much space. Or, ancient history is basically just a retread of Herodotus.
The title of the book is somewhat interesting. What does “Empire of the Mind” allude to? I think the primary point is that after the conquest of the Arabs and the rise of Islam Iranian identity persisted as high culture. For nearly 1,000 years ethnic Iranians were ruled by non-Iranian peoples, primarily Turks. Nevertheless, just like Greek under the Romans, Persian became the prestige language on in a broad zone from Ottoman Anatolia, through Iran proper, and onward into Turco-Muslim India. Just as late 18th-century Russian elites cultivated French, the Ottomans cultivated Persian.
And yet arguably the period when intellectuals of Iranian origin flourished the most was during Golden Age of Islam. It is notable that most of the intellectuals who were patronized and shone under the Abbassids in the decades after 800 A.D. were not Muslim Arabs. There were even some oddball characters, such as Tabit ibn Qurra, a pagan Syrian from Haran. One reason al-Kindi was the “Philosopher of the Arabs” is that he was a tribal Arab. But more typical were Iranians such as Avicenna and al-Razi. If you accept S. Frederick Starr’s argument in Lost Enlightenment and Christopher Beckwith’s in Warriors of the Cloisters Iranians disproportionately from Turan, modern Central Asia, were particularly influential in shaping the high culture and intellectual tone of the world of Islam after 800 A.D.
But this brings up the question which was recently mooted: why were Iranian intellectual achievements so much more notable under Arab Muslims and Turks than when Iranians controlled all the levels of politics, culture, and religion. Who were the great Iranian intellectuals under the Achaemenids, Parthians, and Sassanians?
These Iranian polities (the Achaemenids and Sassanian were Persians from Fars, the Parthians were from the northeast of Iran and not technically Persian) did patronize learning and culture more broadly. The Parthians were notably philhellene, even enjoying Greek theater. In the century before Islam, the Sassanian monarchy sponsored the Academy of Gondishapur, which was notable for its repository of learning in medicine and philosophy. The last Neoplatonists even fled the Byzantine Empire and took refuge in the court of the Shah for several years (before eventually returning due to the terms of a treaty between Byzantium and Persia). And yet from what we know much of the philosophical production at Gondishapur was by Christians of various ethnicities, not Persian Zoroastrians.
There were also efforts and translation and transmission of Indian thought. The Iranian Buddhist city-states were intellectually vibrant, though their long term impact seems to be more influential through their transmission of the religion to China and their inflection of Islam in the 9th century. It is also curious that the Persian national epic was commissioned by a Turkic Muslim.
First, the scale of the Arab Empire was incredible. Iranians integrated into the Arab Muslim Caliphate had access to Egypt and India. Syria and Ferghana. The rise of Islam as an ideological scaffold resulted in civilizational robustness that the Sassanians were incapable of generating. As with the early modern “Persianate world,” the Iranians engaged in an “entryist” strategy, infiltrating and coopting the Arab Empire with the Abbassids (consider the Barmakids and later al-Ma’mun). Iranians were indispensable to the Arab Empire, providing manpower and a royal ideology after the shift away from the west after the fall of the Umayyads.
Second, the domination of military and political roles by Turks after the fall of the Samanids may have facilitated a shift toward civilian pursuits by the Persian elites. I believe a similar dynamic occurred during much of the Roman Empire. For the first few centuries of the Roman Empire, the Greek cities of the east remained under the Roman peace, but its elites remained focused on their own urban life. The vast majority of intellectuals continued to be produced by the Greek-speaking domains. Anastasius in 491 was the first Roman Emperor who was raised as a Greek-speaker, so insular were Greek elites from broader imperial politics.
The bigger message I think is that cultural and civilizational efflorescence can be hard to predict, and the consequence of unforeseen and contingent processes.