What did the Geonim of Babylonia really know about the Jerusalem Talmud?

For over 150 years, scholars have debated a fascinating question: To what extent did the Geonim—the heads of the great academies of Sura and Pumbedita—engage with the Jerusalem Talmud? The Geonim saw themselves as the guardians and transmitters of the Babylonian Talmud, which became the dominant text of Jewish law. But was the Yerushalmi, composed in the Land of Israel, also part of their intellectual world?

My current research is shedding new light on this issue. While working on previously unpublished teshuvot (responsa) from the Geonic period, I have uncovered evidence suggesting that more Babylonian Geonim made use of the Jerusalem Talmud than previously thought.

One of the key figures in this story is Rav Saadia Gaon (882–942), one of the most influential Jewish scholars of the early medieval period. It now seems that Saadia was the first Babylonian Gaon to reference the Jerusalem Talmud—possibly due to his origins in the Jewish community of Egypt, where the influence of Palestinian traditions was stronger.

Among the newly identified responsa, I have found additional examples of Babylonian Geonim, from Saadia onward, quoting from the Yerushalmi. This may prompt us to revisit the long-held assumption that the Geonim relied almost exclusively on the Babylonian Talmud. While they clearly prioritised it, these discoveries suggest that they were also familiar with—and in certain cases actively used—the teachings preserved in the Yerushalmi.

The process of uncovering these responsa has been fascinating. One particular fragment that I am currently working on, T-S NS J511, copied in the 10th century, caught my attention—it is an unknown responsum by Saadia. Although only a small portion of the folio has survived, it clearly contains a direct quotation from the Jerusalem Talmud.

This raises intriguing questions: How did the Geonim access the Yerushalmi? Did they have written copies in Baghdad, or were they relying on oral transmission? And why did they choose to cite it in certain cases but not others?

For now, we do not yet have definitive answers, but each new fragment not only enriches our understanding of halakhic (Jewish legal) discourse but also deepens our knowledge of the intellectual networks that connected Jewish scholars across different regions.

These discoveries were made as part of a joint project between Cambridge's Genizah Research Unit and Machon Yerushalayim to publish newly identified Geonic responsa from the Cairo Genizah. Notably, this project is part of a larger research initiative led by Machon Yerushalayim, which is preparing a new edition of all known Geonic responsa. This ambitious endeavour, carried out by a team of scholars, aims to systematically reexamine the legacy of the Geonim. I have been fortunate to take part in this effort, and with each fragment uncovered, we gain a clearer picture of the rich and complex world of early medieval Jewish scholarship.

Dr Zvi Stampfer is the head of the Multidisciplinary Research Institute for Jewish Studies – Thought, Exploration, and Scholarly Dialogue at Talpiot College, Holon. He is also a lecturer at the Hebrew University and a researcher at Machon Yerushalayim.