For Central Arabia, especially Mecca, there is a lack of epigraphic evidence, but details are found in the writings of Muslim authors of the Abbasid era.
Rwala bedouins also have a similar system, although it is more complete, and includes aṣ-ṣferi, the fifth season, early October-early January, which is lacking from Safaitic attestations.
[10] These seasons were connected to Zodiac signs which, in any case, had a very important place in the pre-Islamic calendars, whether South Arabian or Safaitic.
[11] Below are cited the names of the pre-Islamic Safaitic Zodiac names (ḏ corresponds to voiced English th in the and ṯ to unvoiced English th in throngs), the list of which is incomplete as the word for Cancer is insecure): As in some Safaitic texts, series of Zodiac signs correspond to (in other texts) the same series of months, denoting the same seasons of the year,[12] it is obvious that the Arabian nomads from the desert did not use a 360-days calendar without intercalation, nor a purely lunar calendar, as otherwise Zodiac signs would not match the months and seasons.
[13] However, as Al-Jallad (2016: 86) argues, we would then expect the equivalent Zodiacal sequence to start with Aries, and not with Aquarius as it does (mlḥ w ḏkr w ʔmt).
[16] We have thus the possibility to deduce the general position with the year of the following months, based on the assumption that rabīʿ al-ʾawwal designates, as its name indicates, early autumn.
Some suggested that the Arab pilgrimage festivals in the seventh and twelfth months were originally equinoctial festivals[17] and research on the pre-Islamic calendar has been summarized in recent Islamic[18] and secular[19] scholarship which equates the pre-Islamic months from Muharram to Dhu al-Hijjah with the Hebrew religious months of Iyyar (second) to Nisan (first) respectively (Ramadan corresponding to the Fast of Adam in Tevet) rather than Nisan (first) to Adar (twelfth) as might otherwise be presumed.
[4] The Qur'an links the four forbidden months with Nasi' (Arabic: ٱلنَّسِيء, an-nasīʾ), a word that literally means "postponement".
According to this view, Nasī’ is related to the pre-Islamic practices of the Meccan Arabs, where they would alter the distribution of the forbidden months within a given year without implying a calendar manipulation.
[26] This is corroborated by an early Sabaic inscription, where a religious ritual was "postponed" (ns'’w) due to war.
[4] Thus the Encyclopaedia of Islam concludes "The Arabic system of [Nasī’] can only have been intended to move the Hajj and the fairs associated with it in the vicinity of Mecca to a suitable season of the year.
This interpretation was first proposed by the medieval Muslim astrologer and astronomer Abu Ma'shar al-Balkhi, and later by al-Biruni,[22][28] al-Mas'udi, and some Western scholars.