Nahshon Gaon: Calendar Scholar or Pseudo-author?

This article studies Nahshon Gaon's association with the Jewish calendar. Nahshon ben Zadok Gaon, a ninth-century head of the academy of Sura, is credited with developing a system of calendation known as the Iggul of R. Nahshon, which is considered the Gaon's most reliably attributable work. Based on a corpus of more than 200 medieval and early-modern sources, this article questions the historicity of this attribution. It identifies six different calendar schemes ascribed in the sources to Nahshon Gaon under the title Iggul and demonstrates that such attributions are pseudoepigraphic and predominantly Ashkenazi. Nahshon Gaon's name first appears in late 12th-century Ashkenazi calendar sources, linked to a reiterative calendar for 247 years. Other schemes copied under the title Iggul are later, and their attribution to Nahshon Gaon reflects the fact that the Gaon came to be perceived as a calendar authority.