The Half of the Golden Age Nobody Names

Ask where the science of medieval Baghdad came from and you will be told: Greece.

Aristotle, Euclid, Ptolemy, Galen, preserved in Arabic while Europe forgot them, and handed back at the Renaissance. It is a familiar and largely true story, and it is missing a river.

Four streams, not one

The Abbasid translation movement began under the caliph al-Mansur in the eighth century and peaked under al-Ma'mun in the ninth.

It drew on four separate bodies of learning.

Greek, from Byzantium and from the Syriac-speaking Christian scholars who had already been translating it for two centuries.

Syriac, the working language of those scholars, through which most Greek material actually arrived. The usual route was Greek into Syriac, then Syriac into Arabic.

Middle Persian, from the learning of Sasanian Persia and the academy at Gondishapur.