Jews and Muslims have always lived side by side. Most of the time Jews lived as dhimmis, a protected minority. under Islamic rule. They may not have been loved but they were at least tolerated.

But there was a period when things were far better than that, when Jewish–Islamic relations were indisputably positive. It was an age when Halacha was being clarified, and Sharia law was developing.

Eighth century Baghdad was very different from the sorry place it is now. It was an ambitious, powerhouse of a city, founded by Al-Mansur, the second caliph of the Abbasid dynasty. The Abbasids had come to power in 750, overthrowing the previous Umayyad dynasty. To mark the transition of power, Al-Mansur, built himself a new capital city with the ambition of making it the greatest the world had ever known.

Baghdad at the end of the eighth century assaulted the senses of its visitors as no city had ever done before. In its markets one could find every known herb, fruit and spice, the mingling of their rich scents all but neutralising the heavy odours that steamed off the laden camels and donkeys reluctantly pressing their way along the thoroughfares. Bejewelled wives and daughters of wealthy merchants, decked in coloured satins and gold embroidered silks, on rare excursions from the luxurious palaces in which their menfolk confined them, picked their way delicately over prone, pleading beggars, some maimed, some mad, some simply malingering. Important men in coloured turbans bestrode the streets, their servants hurrying behind, urging along porters weighed down by their burdens. Noise filled the air, the cries of merchants proclaiming their wares, of dogs fighting, children screaming, of the masons hammering on the stones from which the House of Wisdom was being constructed.

The House of Wisdom was the brainchild of Harun Al-Rashid, the caliph whose name is familiar to us from the Arabian Nights, and his son Al-Ma’amun. The caliphate regarded learning as the highest of all virtues. They summed this up in the epithet, ‘The ink of a scholar is more holy than the blood of a martyr’. Inspired by his father’s vision of a Baghdad unmatched by any other in architectural, cultural and scientific grandeur, Al Ma’amun made his dream come true. The House of Wisdom was the city’s library, the place where all the books in the known world were stored.

Baghdad was the intellectual centre of the world and the capital of the expanding Islamic Empire. A little further down the river were the Babylonian yeshivot, the Talmudic academies of Sura, Pumbedita and Mehoza. The great names who we know from the Talmud had long passed away but the geonim, their successors as leaders of the yeshivot were every bit as aspirational as their Islamic counterparts. Each faith had its intellectual giants. And it appears that these giants were more than happy to engage in intellectual discourse with each other.

It’s easy to see the similarities between Talmudic Judaism and Islam. They are each based on a God-given written document – the Torah for Judaism and the Qu’ran for Islam. These divine texts are each interpreted and expanded upon by an explanatory tradition – the Talmud and the Hadith respectively. Both traditions contain legal and ethical material, and the legal material in each distinguishes between religious laws and social laws. The Jewish system of law is called halacha, the Islamic system is called shar’ia. Both names mean a ‘pathway. In fact the two religions are so close in terms of their structure that the great, tenth-century gaon, Saadia, unselfconsciously referred to Jewish law as shar’ia, to the prayer leader in a synagogue as an imam and the direction in which Jews faced when praying as qibla.

The geonim and Islamic scholars grappled with very similar problems; practical, legal issues generated by their shared environment. And their solutions, as embodied in each system of law are often very similar.

Initially Jewish ideas found their way into Islam but the process’s subsequent reversal can be spotted in matters of finance and commerce. Talmudic law matured in Baghdad in a commercial, Islamic environment and the Talmud had already declared that when it came to non-religious matters, ‘The law of the land is the law’. This gave the geonim flexibility to amend or even abrogate Talmudic sanction as necessary.

One example of this flexibility is in the laws governing money transfers. The Talmud had instituted that, as a precaution against fraud, merchants could not transfer money by bills of exchange. However a Geonic ruling overturned this ruling on the basis that people were already doing it, and that it was in accordance with the Islamic laws that regulated merchants.

It is possible that the side by side development of Islamic and Talmudic law was more than a coincidence resulting from a common, shared environment.  It has even been suggested that the caliph, Harun al-Rashid, organized round-table sessions in which leading representatives of the different faiths had the opportunity to exchange ideas.

Whether the intellectual contact between the two faiths was in fact formal or informal, conscious or coincidental, cannot be fully known, But what is undeniable is that two great wonders of human intellectual endeavour were conceived and developed in a shared environment. The Talmud, a stupendous, intellectual work that has never been surpassed in human history, and Islamic law, observed by more people worldwide than any other system, both crystallised in 9th Century Baghdad. Islam today has deep rooted problems, and relations between the two societies have never been so bad. But there was a time when both faiths flourished as a result of their contact with each other. Could it happen again?

You can find out more about me and my books on my website: http://www.harryfreedmanbooks.com/

The Talmud, A Biography by Harry Freedman will be published by Bloomsbury in the USA in the fall. http://www.bloomsbury.com/us/the-talmud-a-biography-9781472905949/