Was the Islamic golden age an interfaith utopia or a prolonged period of subjugation for the Jews and Christians? Why is this period also called the golden age of Jewish-Muslim relations? The truth is probably in between the two extremes, as I will explain in a moment. And what caused the Islamic golden age to fall, and specifically how did the Jewish-Muslim relationship deteriorate near the end of this golden era?
Some of the best reviews on this topic come from Mark Cohen, professor of Religion at Princeton University, and a good friend of mine, Rabbi Reuven Firestone, professor of Medieval Judaism and Islam and Hebrew Union College in Los Angeles. (In the spirit of disclosure, I must disclose that he has written testimonials for my two books, The Quran: With or Against the Bible? and The Three Abrahamic Testaments. I consider him an expert, so the references to his authority are based not just on mutual respect and friendship but rather his extensive work and expertise in this area).
Mark Cohen in his prologue of the book, The Golden Age of Jewish-Muslim Relationship: Myth and Reality, starts with a Jewish perspective of the era.
In the nineteenth century there was nearly universal consensus that Jews in the Islamic Middle Ages—taking al-Andalus , or Muslim Spain , as the model—lived in a “Golden Age” of Jewish-Muslim harmony, an interfaith utopia of tolerance and convivencia. It was thought that Jews mingled freely and comfortably with Muslims, immersed in Arabic-Islamic culture, including the language, poetry, philosophy, science, medicine, and the study of Scripture—a society, furthermore, in which Jews could and many did ascend to the pinnacles of political power in Muslim government. This idealized picture went beyond Spain to encompass the entire Muslim world, from Baghdad to Cordova , and extended over the long centuries, bracketed by the Islamic conquests at one end and the era of Moses Maimonides (1138–1204) at the other. The idea stemmed in the first instance from disappointment felt by central European Jewish historians as Emancipation-era promises of political and cultural equality remained unfulfilled. They exploited the tolerance they ascribed to Islam to chastise their Christian neighbors for failing to rise to the standards set by non-Christian society hundreds of years earlier.
After this introduction, he goes on to give his own take on the era.
The interfaith utopia was to a certain extent a myth; it ignored, or left unmentioned, the legal inferiority of the Jews and periodic outbursts of violence. Yet, when compared to the gloomier history of Jews in the medieval Ashkenazic world of Northern Europe and late medieval Spain , and the far more frequent and severe persecution in those regions, it contained a very large kernel of truth.
One of the criticism of the Islamic golden age is that the non Muslims were considered Dhimmi and were subject to an annual poll tax, or Jizya. Like Jihad, Hijab and Shariah, these two words are also rather misunderstood. Here is a definition of Dhimmi from Merriam-Webster dictionary.
..a person living in a region overrun by Muslim conquest who was accorded a protected status and allowed to retain his or her original faith.
The truth is that the Jews, even in their Dhimmi status enjoyed a lot of freedom and prospered in the golden age of Islam. Professor Rabbi Firestone in his article that is part of the Oxford Research Encyclopedias goes on to explain this in more details.
The term used to define the status of tolerated religions was dhimma, which meant protection. The people belonging to tolerated religions were called ahl al-dhimma—“protected people,” or in shortened form, dhimmīs. Dhimmīs were obligated to pay an annual tax and to abide by the sumptuary laws. Their “protection” meant that they were legal citizens of the state and protected by the same basic laws that protected Muslim citizens, though at a subordinate level. For example, they could bring grievances to a Muslim court of law, but their witnessing was not as powerful as that of Muslims so they were required to bring twice the number to court. They could pray undisturbed in their houses of worship, but unlike Muslims they were forbidden from public displays of religion. Dhimmīs were forbidden from building new houses of worship or repairing those already established, except with permission of the ruler. Their status, though certainly not equal and therefore unacceptable by today’s democratic standards, was nevertheless a significant improvement over their position in the Christian world where the “Jewry laws” identified Jews as an aberrant community and where Jews eventually lost their protected status altogether. By the High Middle Ages, Jews were able to survive in Christendom only through the largess of noble families who personally protected them but only for as long as the nobility wished, a far more unstable and dangerous situation than they experienced generally under Muslim rule.
These rules were based on a pact that is widely known as the pact of Umer. Historians also go on to state that even though Jews were not supposed to build new synagogues and be part of the ruling Caliphate, many Jews worked side by side with their Muslim counterparts in various areas such as science, art, music, trade and even achieved the stats of vizier and personal physician of Caliph. The main criteria used to achieve the high status were whether they were skilled and qualified. Jews also went through a period of religious reformation of sorts and were free to explore Jewish theology. In his Oxford University Press article, Professor Rabbi Firestone goes on to state:
The Jews who lived in the early Muslim world were also busy consolidating Rabbinic Judaism and its core texts of Talmud and the legal literature that was just beginning to emerge from it. For example, two primitive attempts to codify Jewish law from Rabbinic literature that emerged in the Muslim world in the 8th century are the Shʾiltot (“Questions”) and the Halakhot Pesuqot (“Law as Decided”). While Jews and Muslims were interfacing at all levels, we have little concrete information about it. Certainly, given the Jewish historical penchant for recording disasters that affected them, if relations were very bad we would know about it, so it must be presumed that Jews and Muslims lived together reasonably well under the conditions established in the Muslim world during the early period. …..
The Jews of Islam were profoundly and enduringly influenced by the development among their Muslim compatriots of “the sciences of the Qurʾān” (ʿulūm al-qurʾān). These include lexicography and etymology, the study of Arabic grammar (word morphology, syntax, etc.), rhetoric of the Qurʾan and ancient Arabic literatures,……
Jewish thinkers were profoundly influenced by other popular sciences in the Muslim world, such as philosophy, astronomy, optics, medicine, and others. In fact, although Jews were exposed to systematic thinking in philosophy and theology under the Hellenistic influence of late antique Palestine, it was rejected by Rabbinic Jews and became of interest only after it had been effectively endorsed by Muslims who engaged with it. Developments in all of these fields in the Muslim world were paralleled among Jews in the same environments.
That the Jews and Muslims worked side by side during the golden age was not a myth. Professor Firestone refers to this relationship based on a discovery of documents found in a Cairo synagogue.
Al-Andulus, the Muslim Spain was close to an interfaith utopia, at least in its early and middle parts. Towards the end, the situation worsened when the fundamentalist Almohads took over in 1148 CE and abolished the Dhimmi status, forcing many Non Muslims (and Muslims who did not comply with their extreme brand- sounds familiar?). Those who fled included famous Jewish theologian and physician, Moses Maimonides. He became personal physician of the Caliph, and a leader in Jewish thought.
The documents include public and private records, personal letters, and much other information not only about Cairo but about many other Mediterranean lands, and they also contain much information about Muslims and the relations between the two communities. These include information about business partnerships between Jews and Muslims such as silversmiths and glassworkers, who shared partnership in their shops with each taking off on his own weekly holiday, the Muslims on Friday and Jews on Saturday.
Bernard Lewis also took a jab at the Jewish-Muslim relationship:
Generally, the Jewish people were allowed to practice their religion and live according to the laws and scriptures of their community. Furthermore, the restrictions to which they were subject were social and symbolic rather than tangible and practical in character. That is to say, these regulations served to define the relationship between the two communities, and not to oppress the Jewish population.
During the golden age, Jews prospered in many areas, gaining access to the Caliph’s courts and palaces in high positions. 
Especially after 912, during the reign of Abd-ar-Rahman III and his son, Al-Hakam II, the Jews prospered culturally, and some notable figures held high posts in the Caliphate of Cordoba. Jewish philosophers, mathematicians, astronomers, poets, and rabbinical scholars composed highly rich cultural and scientific work. Many devoted themselves to the study of the sciences and philosophy, composing many of the most valuable texts of Jewish Philosophy. Jews took part in the overall prosperity of Muslim Al-Andalus. Jewish economic expansion was unparalleled.
‘Abd al-Rahman’s court physician and minister was Hasdai ibn Shaprut, the patron of Menahem ben Saruq, Dunash ben Labrat, and other Jewish scholars and poets. In following centuries, Jewish thought flourished under famous figures such as Samuel Ha-Nagid, Moses ibn Ezra, Solomon ibn Gabirol and Judah Halevi. During ‘Abd al-Rahman’s term of power, the scholar Moses ben Enoch was appointed rabbi of Córdoba, and as a consequence al-Andalus became the center of Talmudic study, and Córdoba the meeting-place of Jewish savants.
These views are supported by other Jewish authorities and societies. Rebecca Weiner on the subject of Judaism: Sephardim on Jewish Virtual Library confirms the writings of other experts.
The era of Muslim rule in Spain (8th-11th century) was considered the “Golden Age” for Spanish Jewry. Jewish intellectual and spiritual life flourished and many Jews served in Spanish courts. Jewish economic expansion was unparalleled. In Toledo, Jews were involved in translating Arabic texts to the romance languages, as well as translating Greek and Hebrew texts into Arabic. Jews also contributed to botany, geography, medicine, mathematics, poetry and philosophy.
A number of well-known Jewish physicians practiced during this period, including Hasdai Ibn Shaprut (915-970), who was the doctor for the Caliph (leader of Spain). Many famous Jewish figures lived during the Golden Age and contributed to making this a flourishing period for Jewish thought. These included Samuel Ha-Nagid, Moses ibn Ezra, Solomon ibn Gabirol Judah Halevi and Moses Maimonides.
It is important to remember that the Islamic golden age was not limited to one area or even a few generations. It expanded from Cairo, to Baghdad, to North Africa and the Andalusia (Muslim Spain with Cordoba at the heart of civilization). It went through ups and downs in interfaith relations, tolerance and inclusiveness within the golden age, with Baghdad and Cordoba perhaps the two most shining examples of advances in knowledge, learning, science and art, as well as interfaith relationships. And in the 15th to 17th century, Ottoman empire also attracted many Jews who were expelled or those who fled from the Spanish peninsula under Christian rule and the inquisition.
Rabbi Reuven Firestone sums up the relationship and its ups and downs beautifully on his oxford university Press article.
As a rule, when the economic and political situation in the Muslim world was stable, so was the position of its Jews. Relations between Jews and Muslims improved through business and commerce, and that positively impacted social relations as well. During periods of destabilization, however, the general relations between Muslims and Jews deteriorated, though always with exceptions.
Violence against the Jews and other minorities did erupt from time to time, most notably after the Almohads took over in the mid 12th century in Morocco and later Andalusia. Many Jews and Christians were forced to convert, flee or got killed. Maimonides urged his followers to superficially convert, as he preferred that over martyrdom. He himself fled to more tolerant part of the Islamic empire, and settled in Cairo.
So the golden question is: what happened that brought the fall of the golden age?
The answer is not that simple. Many articles and books have been written. The Mongol invasion in 1258 was partly responsible. They burned hundreds of thousands of books and the libraries. The crusades caused further loss of power. Europe went through renaissance after the discovery of the new world-America beginning in the 15th century. There were infightings. The power probably got to their heads. The fundamentalists Almohads take over in the thirteenth century caused exodus of the Jews and other minorities as well as Muslims who did not identify with the extreme brand played a role. Some even blame Imam Al Ghazali, an Asharite, for his views that allegedly opposed the critical thinking, though there are counter arguments as well.
I will repeat the questions I posed on my first article in this series.
The Islamic golden age is long gone. We the Muslims need to engage in a collective introspection to figure out what made the past Muslim societies the center of wisdom and knowledge, and why we are no longer the top performers. Have we become exclusivists in our societies? Have we stopped pondering? Have we not misused the Qur’an for our selfish interpretations to suit our needs and pre-set beliefs? Have we not rendered the Qur’an a book to stay in the book shelves to bring ‘barakah’? Have we stopped learning about the great thought leaders of the yesteryears, and instead have latched on to the self-proclaimed “religious scholars”? Is critical thinking part of the discourse and the educational system?
Lewis, Bernard W (1984). The Jews of Islam