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A Popular Calendar

by Nadia Vidro


The calendar is essential for Jewish religious life, and it was important for every medieval Jewish community to have one. The standard Rabbinic calendar is fixed by a calculation, which must be performed on a regular basis. This calculation, although well-known, involves complex arithmetical operations beyond the numerical proficiency of most medieval Jews.

An ingenious calendar scheme was developed that allowed people with little calendar knowledge to be able to set the calendar. This scheme is based on the assumption that the calendar repeats itself exactly every 247 years. The attraction of this cycle is that it can be calculated once and used forever; its danger – that it diverges from the standard calendar for a few years every century. By using the 247-year calendar even those communities that did not have a calendar-maker could, for most years, follow the correct Jewish calendar. In those years when the 247-year cycle produced false results, its users ran the risk of celebrating major religious holidays at the wrong times, eating leavened bread on Passover or not fasting on the Day of Atonement.

The oldest traceable 247-year calendar cycles are found in the Cairo Genizah and appear to have been put together in the middle of the 10th century. They are attributed to Josiah b. Mevorakh al-ʿĀqūlī (or ibn al-ʿĀqūlī), a little-known scholar of Babylonian descent who was still alive in 1009. His nisba al-ʿĀqūlī may refer to ʿĀqūlā, a pre-islamic (Syriac) name of Kūfa, or to Dayr al-ʿĀqūl, a town on the Tigris southeast of Baghdad.

Josiah b. Mevorakh al-ʿĀqūlī’s work on the calendar consists of an introduction followed by fourteen chapters, each dedicated to one of the fourteen possible courses of the Jewish year. The introduction has been fully preserved in T-S 10K20.2.

בש֗ רח֗

קאל יאשיהו בן מבורך בן אלעאקולי רצ֗י

אללה ענה אדא ארדת תערף רווס אל

שהור ואלאעיאד פכד סני אלאסכנדר

מע אלמטלובה ואסקט מנהא אלף סנה

ומא יתבקי אסקטה ר֗מ֗ז֗ ר֗מ֗ז֗ ואלדי

יבקי מע[ך] בעד דלך אטלבה עלי הדה

אלאלואח אלת[י] בין [י]דיך אדא וגדתה תקרא

תחת אללוח תג֗ד אלשהור ואלאעיאד צחיחה

כמא תשתהי אן שא אללה תעאלי


In the name of God

Josiah b. Mevorakh b. al-ʿĀqūlī, may God be pleased with him, said: if you want to know the beginnings of months and the festivals, take the years of Alexander including the required (year), deduct from them 1000 years, and cast out 247s from what remains. What is left after this, look it up in the tables that you have before you, and when you find it, read what is under the table and you will find the correct months and festivals as you wanted, God willing.


Each chapter of Josiah b. Mevorakh al-ʿĀqūlī’s calendar is made up of three elements: 1) a set of numbers, 2) the main calendrical characteristics of the year described in that chapter, and 3) a fuller description of the calendar, including the beginning of months, festivals and fasts. An example from the best-preserved booklet T-S K2.8 is:

ק֗י֗ח֗ ק֗ל֗ב֗ ל֗ד֗ כ֗ י֗ז֗ י֗ י֗ג֗

ז֗ ל֗ז֗ מ֗ ס֗ז֗ ס֗ד֗

ס֗א֗ מ֗ז֗ מ֗ד֗ ע֗ד֗ פ֗ה֗ צ֗א֗

פ֗ח֗ ק֗ט֗ו֗ ק֗י֗ב֗ ק֗ח֗ ק֗ה֗

צ֗ד֗ ק֗ל֗ה ק֗ל֗ט֗ ק֗מ֗ב֗ ק֗מ֗ה֗

ק֗נ֗ט֗ ק֗ס֗ב֗ ק֗ס֗ה֗ ק֗ס֗ט֗

ק֗פ֗ג֗ ק֗פ֗ו֗ ר֗י֗ו֗ ר֗ל֗ ר֗י֗

ר֗י֗ג֗ ק֗צ֗ו֗ ר֗ג֗ ק֗פ֗ט֗

ר֗ל֗ז֗ ר֗מ֗ ר֗מ֗ג֗



תשרי ה֗ יום הכפורים ז֗

סוכה ושמיני עצרת ה֗

ערבה ד֗ מרחשון ו֗ז֗ כסלו א֗ ....


118, 132, 34, 20, 17, 10, 13

7, 37, 40, 67, 64

61, 47, 44, 74, 85, 91

88, 115, 112, 108, 105

94, 135, 139, 142, 145,

159, 162, 165, 169,

183, 186, 216, 230, 210,

213, 196, 203, 189,

237, 240, 243


Tišri: Thursday; day of Atonement: Sabbath;

Sukkot and Šemini ʿAṣeret: Thursday;

(day of the) Willow: Wednesday; Marḥešvan: Friday and Sabbath; Kislev: Sunday


In order to use Josiah b. Mevorakh al-ʿĀqūlī’s calendar in any given year, all one needs to know is that year’s Seleucid date. One takes the date and determines the year’s position within the 247-year cycle by following the algorithm described in the introduction. One then looks for it within the sets of numbers given in each of the fourteen chapters. The chapter that lists the relevant number will describe the correct course of the year for that date. Take, for example, the current year 5778 AM. Its Seleucid date is 2329 SE, and it’s number according to Josiah b. Mevorakh al-ʿĀqūlī’s algorithm is 94. The number 94 can be found on the list of numbers edited above. This means that in 2329 SE (5778 AM) the month of Tišri will start on a Thursday, the Day of Atonement will be on a Sabbath, the first day of Sukkot as well as Šemini ʿAṣeret will fall on a Thursday, and so on.

This cycle was popular in every sense of the word: it was accessible to the general public and was widely used. T-S NS 98.2, a fragment on the history of calendar, reports:

We saw that people often rely on the calendar of R. Josiah b. Mevorakh of blessed memory because it is simple and easy to grasp. We intentionally collated many versions of it and found them significantly different and there is not among them a correct one.

The surviving fragments themselves furnish evidence of having been used in practice. In T-S K2.41, fol. 3r a user remarked “this is our blessed year” (הדה סנתנא אלמבארכה) and, switching to Arabic characters, wished the year to be happy (سعيدة). His year happened to follow the same course as the one that began this month and we join the medieval writer in hoping that this year will be happy and blessed!

T-S K2.41 P3 recto



Raḥamim Sar-Shalom, Gates to the Hebrew Calendar (Netanyah: R. Sar-Shalom, 1984) (Hebrew)

Sacha Stern, Calendar and Community. A History of the Jewish Calendar, 2nd cent. BCE – 10th cent. CE (Oxford: Oxford University Press, 2001)

Yosef Tobi, The Jews of Yemen. Studies in Their History and Culture (Leiden: Brill, 1999), pp. 211–226

Nadia Vidro, ‘The Origins of the 247-year Calendar Cycle’, Aleph 17.1 (2017), pp. 95–137


My research is funded by the ERC Advanced Grant project ‘Calendars in Late Antiquity and the Middle Ages: Standardization and Fixation’ running at UCL.


Cite this article

Vidro, N. A Popular Calendar. [Genizah Research Unit, Fragment of the Month, September 2017].

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