Aharon ben Meir אהרן בן מאיר
who declared his own calendar—and split the people for two years
The sanctification of the month had been the right of the Land of Israel from antiquity; but the fixed calendar introduced in the fourth century made the reckoning common—and therefore disputable. In 4682 (922 CE) Aharon ben Meir, head of the academy of the Land of Israel, declared that by his calculation the molad of Tishrei fell otherwise, and set the festivals two days earlier than they were reckoned in Babylonia.
The dispute ran two years and was not arithmetical but about authority: who has the right to fix the calendar—the heirs of the Sanhedrin in the Land of Israel, or the Geonim of Babylonia, under whom the whole diaspora learns. Against ben Meir stood the still-young Saadya, future Gaon of Sura; he wrote to the communities, taking the calculation apart on its merits, and the communities followed him.
Babylonia's victory in that dispute decided more than two days of Pesach: it fixed a single calendar for the whole Jewish world and shifted the centre of gravity eastward. The dispute itself was almost forgotten until letters from both sides turned up in the Cairo Genizah.
The years are taken from the Epistle of Rav Sherira Gaon—the letter of 4747 (987), the only source in which the age of the Savoraim is set out by name and year. There is no other testimony, and that should be kept in mind.
On the timeline
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Sources
Documents of the period
- Cairo Genizah letters on the calendar dispute — the correspondence of the parties, 4682–4684
- Saadya Gaon, Sefer haMoadim — the analysis of ben Meir's calculation
Basis: documents and evidence.