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Muslim and Christian calendars in Jewish calendar booklets: T-S K2.33

Nadia Vidro

The medieval Middle East was a multi-cultural society in which Jews lived alongside Muslims and Christians of various denominations. These different groups had their own calendars. The knowledge of Muslim and Christian calendars and their dates of festivals are reflected in Jewish calendar booklets preserved in the Cairo Genizah.

Calendar booklets were practical calendars that described the course of a number of Jewish years. Unlike today, in the Middle Ages it was customary to have a calendar for more than one year. A calendar booklet usually covered between 19 and 57 years. For each year, it gave the date according to a number of Eras, mentioned how many months were in that year and described in detail the course of the year, including the days of the week of beginnings of Jewish months, festivals and fasts and some additional information. While calendar booklets in the Cairo Genizah were mainly concerned with the Jewish calendar, they often included information on the Muslim and Coptic calendars, and sometimes on the Julian calendar, too.

The Jews’ familiarity with the Muslim calendar is well known. Many traders’ letters, legal documents and accounts are dated according to the Era of the Hijra. It is thus not surprising that Hijra dates (figure 1), correspondences between Jewish and Muslim months and Muslim festivals were often mentioned in Jewish calendar booklets. The Hijra date could be referred to in a number of ways, including ‘of the Hijra’, ‘of the Arabs’, ‘of the goyyim’, and ‘according to the counting of the Ishmaelites’.


cut-out from image of T-S K2.59 verso

Figure 1. T-S K2.59 verso, in the hand of Ḥalfon ben Manasse. The beginning of the year 522 of the Hijra is noted in Arabic characters in the margins of a Jewish calendar for the year 1127/8 CE.


A smaller number of Jewish calendar booklets included information on the Coptic calendar, such as correspondences between the Jewish and the Coptic months, Coptic festivals or Coptic dates of the Jewish tequfot (equinoxes and solstices). Dating the tequfot by the Coptic calendar was a matter of convenience, because tequfot move in the Jewish calendar but always fall on the same dates in the solar Coptic calendar (Figure 2).


cut out of image T-S K 2.25 P2 recto

Figure 2. T-S K2.25 P2 recto, left. The tequfa of Tishri is said to be on the 27th of the Coptic month Thout (תות).


It is even rarer to find correspondences with Julian months (Figure 3).


cut out of T-S K2.94 recto

Figure 3. T-S K2.94 recto. Av of the year 4823 of the Era of Creation (1063 CE) is said to correspond to [the end of] the Muslim month Jumādā al-Ākhira, and to July (יוליה).


The most complete information on the Muslim and Coptic calendars is incorporated in calendar booklets prepared by Yedutun ha-Levi, the famous cantor of the Palestinian community of Fusṭāṭ in the 13th century.1 A number of calendars in his hand are preserved in the Cairo Genizah, among them T-S K2.33 for 1233/4 CE.2

title of image here

T-S K2.33 P2 recto


T-S K2.33 is dated as follows:3

אלסנה... דתתקצד ליצירה בתקמו ליציאת מצ[רים] אתקמה לשטרות אקסו לחרבן... תתקנ ללקבט והי אליט מן דור אלכ֗מסין כמל דור אלנ֗ והי אלת֗אניה מן אלת֗לת֗ סנין אלבסיטה תרל ללערב

Year... 4994 of the Era of Creation, 2546 of the Era of the Exodus, 1545 of the Seleucid Era, 1166 of the Era of the Destruction of the Second Temple... [Year] 950 of the Copts. It is [year] 19 in the 50th cycle, which is the end of cycle no. 50, and it is the second of three plain years. [Year] 630 of the Arabs.


These dates, given according to the Jewish, Coptic and Muslim Eras, correctly correspond to 4994 of the Era of Creation (1233/4 CE), although Tishri of that year fell at the end of the Hijra year 630 AH.

The fragment then describes in great detail the course of the Jewish year 4994 of the Era of Creation and includes the following data on the Muslim and Coptic calendars:


Jewish month

Muslim calendar (beginnings of months and dates of festivals)

Coptic calendar (beginnings of months and dates of festivals)

P2r Tishri Ḏū al-Ḥijjah of the year 630 AH begins on Wednesday, 2 Tishri. Al-ʿīd al-kabīr is on Friday, 11 Tishri. Paopi (באבה) begins on Wednesday, 23 Tishri.
P2r–P1r, left Marḥeshvan Muḥarram of 631 AH begins on Thursday, 1 Marḥeshvan. This is the beginning of the cycle no. 22. Hathor (התור) begins on Friday, 23 Marḥeshvan.
P1r, left Kislev Ṣafar begins Saturday, 2 Kislev. Koiak (כיהך) begins on Sunday, 24 Kislev.
  Ṭevet Rabīʿ al-Awwal begins on Sunday, 1 Ṭevet. Christmas is on Sunday, 22 Ṭevet, 29 Koiak. Tobi (טובי) begins on Tuesday, 24 Ṭevet.
  Shevaṭ Rabīʿ al-Ākhir begins on Tuesday, 2 Shevaṭ. Meshir (אמשיר) begins on Thursday, 25 Shevaṭ. Shrovetide is on Sunday, 4 Meshir, 28 Shevaṭ, 27 Rabīʿ al-Ākhir. Their fast begins on Monday, 5 Meshir, 29 Shevaṭ, 28 Rabīʿ al-Ākhir.
P1r, left-P1v, right Adar Jumādā al-Awwal (sic!) begins on Wednesday, 1 Adar. Paremhat (ברמהאת) begins on Saturday, 25 Adar.
P1v, right Nisan Jumādā al-Ākhir (sic!) begins on Friday, 2 Nisan. Parmouti (ברמודה) begins on Monday, 26 Nisan. Christians break their fast on that day, which is 25 Jumādā al-Ākhir.
  Iyyar Rajab begins on Saturday, 1 Iyyar. Pashons (בשנס) begins on 26 Iyyar.
P1v, right–P1v, left Sivan Shaʿbān begins on Monday, 2 Sivan. Paoni (בוונה) begins on Friday, 27 Sivan.
P1v, left Tammuz Ramaḍān begins on Tuesday, 1 Tammuz. Epip (אביב) begins on Sunday, 27 Tammuz.
  Av Shawwāl begins on Thursday, 2 Av, which is al-ʿīd al-ṣaghīr, i.e. ʿīd al-fiṭr. Mesori (מסרי) begins on Tuesday, 28 Av.
P1v, left–P1r, right Elul Ḏū al-Qaʿda begins on Friday, 1 Elul. The five epagomenal days (כ֗מס אלנסי), which is their ‘little month’,4 begin on Thursday, 28 Elul.
P1r, right Next Tishri Ḏū al-Ḥijjah begins on Sunday, 2 Tishri. Al-ʿīd al-kabīr, i.e. ʿīd al-naḥr, is on Tuesday, 11 Tishri. Thout and the Coptic New Year are on Tuesday, 4 Tishri. The year 951 is the beginning of the 19-year cycle no. 51, and is the third of three plain years.


As the above table shows, Yedutun ha-Levi provided the following information on the Muslim calendar: the Hijra date of the first Jewish month Tishri, the beginning of the new Muslim year, and the dates in the Jewish calendar when Muslim months begin and when main Muslim festivals occur. Only two festivals are mentioned: the Great Festival (al-ʿīd al-kabīr), also called the Festival of Immolation (ʿīd al-naḥr), better known today as ʿīd al-adḥā, and the Lesser Festival (al-ʿīd al-ṣaghīr) or ʿīd al-fiṭr, the breaking of the Ramaḍān fast. As is well known, months in the Muslim calendar begin at the first appearance of the lunar crescent. As such, it is impossible to know in advance when a Muslim month will begin and to establish correspondences between the empirically established Muslim months and the calculated Jewish months. However, a different, schematic calendar was used by the Muslims for administrative needs, such as taxation, and for astronomical computations (the same calendar is now used in online calendar converters).5 In this calendar, months with odd numbers (the first, third, etc.) have 30 days and months with even numbers (the second, fourth, etc.) have 29 days. Yedutun’s data on Muslim months agrees with this schematic calendar; the actual Muslim dates that year would have been slightly different. In addition, in 19 out of every 30 schematic Muslim years an extra day is added at the end of the last month Ḏū al-Ḥijjah, making it 30 days long. A reference to this 30-year cycle is found in the calendar for Marḥeshvan, where it is said that a new cycle no. 22 begins in the year 631 of the Hijra (631=21x30+1).

The Coptic calendar is represented in Yedutun ha-Levi’s calendar booklet by the year’s date according to the Coptic Era, and the dates in the Jewish calendar when Coptic months begin and when main Coptic festivals and fasts occur. The mentioned festivals include the New Year (nayrūz), Christmas (al-mīlād), Shrovetide (rifāʿ), and the beginning and end of Lent (‘their fast’). The date of Easter is not explicitly given. It is worth noting that dates of Coptic festivals are given according to both the Jewish and the Muslim calendar, while Muslim festivals are dated only according to the Jewish calendar. Obviously, Yedutun thought it useful for Jewish readers to know the dates of the Coptic calendar according to their own and the majority calendar, but saw no need to provide the Coptic dates of events in the Muslim calendar.

Beside the individual events in the Coptic calendar, information is provided on the years themselves. In the Coptic calendar, every fourth year is a leap year, meaning that an extra day is added at its end (i.e. the ‘little month’ has six rather than five epagomenal days, see Elul in the table). In our case, year 950 was the second of three years between such leap years and year 951 – the third. The Coptic date of Easter is determined by a calculation based on the Alexandrian 19-year cycle, which synchronises the lunar months with the solar years of the Coptic calendar. Year 950 is described as the last year of the 19-year cycle no. 50 (19x50=950), and year 951 – as the beginning of the next cycle no. 51.

Same as their European brethren who copied Christian calendars in Hebrew, Jews in the Middle East needed to know about the Muslim and Christian calendar in order to coordinate their socio-economic life with that of their Muslim and Christian neighbours.6 Besides, these calendars may have been useful for creating horoscopes – at least one birth record has been found that gives a person’s date of birth according to the Seleucid and Coptic Eras and the Era of the Hijra (T-S Ar.54.74, 1197 CE). The Hijra calendar may have also played a unifying role in the life of medieval middle eastern Jewish communities, which practiced more than one Jewish calendar. All Rabbanites followed the same calculated calendar, which is the calendar in the booklets discussed here. But the Qaraites relied on a calendar that was based on the observation of natural phenomena such as the first appearance of the lunar crescent and the ripening of barley crops in Palestine. As a result of these different approaches to calendar reckoning, Rabbanites and Qaraites often began months some days apart and celebrated Jewish festivals on different dates and sometimes even in different months. Besides, the Qaraite calendar itself was not standardised, so that different groups of Qaraites also kept different dates. The Hijra calendar may have provided a common timeframe for all Jewish groups, although more research is required to confirm or disprove this suggestion.


Research for this Fragment of the Month was funded by the British Academy/Leverhulme small research grant ‘Calendar fragments as a tool for palaeography’ which ran at Cambridge University Library in 2018–2020 (PI Ben Outhwaite).



1 Elizur, Sh. שירי ר' ידותון הלוי החבר in Dine Israel – Studies in Halakhah and Jewish Law 26–27 (2009/2010), pp. 301–308 [Hebrew section].

2 Other parts of the same booklet are preserved in ENA 3740.11–12 and AIU VIII.E.23.

3 I include only the dates according to various Eras and information on the Muslim and Coptic calendar but omit other parts of the dating, such as the position of the year in the Jewish 19-years cycle, Sabbatical and jubilee cycles which are irrelevant in the present context.

4 In the Coptic calendar, the year is 365 days long and consists of twelve 30-day months followed by 5 intercalary days known as ‘the epagomenal days.’ De Blois, F.C., Van Dalen, B., Humphreys, R.S., Marin, Manuela, Lambton, Ann K.S, Woodhead, Christine, Athar Ali, M., Hunwick, J.O., Freeman-Grenville, G.S.P., Proudfoot, I. et al., “Taʾrīk̲h̲”, in: Encyclopaedia of Islam, Second Edition, Edited by: P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Consulted online on 05 March 2021.

5 De Blois, F.C., Van Dalen, B., Humphreys, R.S., Marin, Manuela, Lambton, Ann K.S, Woodhead, Christine, Athar Ali, M., Hunwick, J.O., Freeman-Grenville, G.S.P., Proudfoot, I. et al., “Taʾrīk̲h̲”, in: Encyclopaedia of Islam, Second Edition, Edited by: P. Bearman, Th. Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Consulted online on 05 March 2021.

6 On Christian calendars in late medieval and early modern European Jewish calendar manuals known as Sifre Evronot see Carlebach, E. Palaces of Time : Jewish Calendar and Culture in Early Modern Europe. Cambridge, Mass. ; London: Belknap, 2011, pp. 115–140. Stern, S., A Christian liturgical calendar in Hebrew. Genizah Fragments (70), 2015, p. 3. Stern, S., Christian Calendars in Medieval Hebrew Manuscripts. Medieval Encounters, Volume 22, Issue 1-3, 2016, pp. 236 – 265.


Cite this article

Vidro, N. (2021). Muslim and Christian calendars in Jewish calendar booklets: T-S K2.33. [Genizah Research Unit, Fragment of the Month, March 2021].


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