The predecessor to the Islamic calendar - the pagan Arabian - was a luni-solar calendar which used lunar months, but was also synchronized with the seasons by the insertion of an additional, intercalary month, when required.
Whether the intercalary month (nasi) was added in the spring like that of the Hebrew calendar or in autumn is debated. It is assumed that the intercalary month was added between the twelfth month (the month of the Pagan Hajj) and the first month (Muharram) of the Pagan year.
The two Rabi' months denote grazing and the modern Meccan rainy season (only slightly less arid than normal), which would promote the growth of grasses for grazing, occurs during autumn. These imply a pre-Islamic, Pagan year beginning near the autumnal equinox. However, the rainy season after which these months are named may have been different when the names originated (before Muhammad's time) or the calendar may have been imported from another region which did have such a rainy season.
On the other hand, in the ninth year after the Hijra, as documented in the Quran(9:36-37),Allah revealed the prohibition of the intercalary month thus (releasing the calendar from the seasons) which implies once more a pre-Islamic, Pagan year beginning near the vernal equinox because that is when the modern lunar year began during his last year.
Each month has either 29 or 30 days, but usually in no discernible order. Traditionally, the first day of each month was the day (beginning at sunset) of the first sighting of the lunar crescent (Hilal) shortly after sunset. If the Hilal was not observed immediately after the 29th day of a month, either because clouds blocked its view or because the western sky was still too bright when the moon set, then the day that began at that sunset was the 30th.
*** The Jews, following the Bible, start the 'next day' in the evening when sighting the first star. Muhammad, as usual when it came to religious traditions, copied it from them ***
According to Muhammadan Islam, the number of months with Allah has been twelve months by Allah's ordinance since the day he created the heavens and the earth. Of these, four are known as sacred-
9: 36The number of months in the sight of Allah is twelve (in a year) so ordained by Him the day He created the heavens and the earth; of them four are sacred; that is the straight usage. So wrong not yourselves therein and fight the pagans all together as they fight you all together. But know that Allah is with those who restrain themselves.
37Verily the transposing (of a prohibited month) is an addition to unbelief: the unbelievers are led to wrong thereby: for they make it lawful one year and forbidden another year in order to adjust the number of months forbidden by Allah and make such forbidden ones lawful. The evil of their course seems pleasing to them. But Allah guideth not those who reject faith.
This prohibition was repeated by Muhammad during his last sermon on Mount Arafat which was delivered during his farewell pilgrimage to Mecca on 9 Dhu al-Hijja
The following paragraph is often deleted from the sermon by its modern editors as being unimportant:
" O People, the unbelievers indulge in tampering with the calendar in order to make permissible that which Allah forbade, and to forbid that which Allah has made permissible. With Allah the months are twelve in number. Four of them are holy, three of these are successive and one occurs singly between the months of Jumada and Shaban.
The three successive holy months mentioned by Muhammad are Dhu al-Qada, Dhu al-Hijja, and Muharram, thus excluding an intercalary month before Muharram. The single holy month is Rajab. These months were considered holy both within the new Islamic calendar and within the old pagan Meccan calendar. The sequence of intercalary months before they were eliminated, and hence the first year during which a scheduled or arbitrarily decreed intercalary month did not occur, is unknown.
These were four months of truce during which all hostilities, blood feuds, raids and all acts of warfare and aggression were suspended so that the pagan Arabs can dedicate themselves to their idols by giving sacrifices, going on pilgrimage to holy sites, trading as well as sporting events both physical and poetical "
These months were dhu al Qa'dah, dhu al Hijjah, Muharram and Rajab being represented by the 11th, 12th 1st and 2nd months of the year. The first three were especially dedicated for religious purposes and the last for trading and secular activities.
*** Muhammad, for obvious reasons, had no choice but to include these previously Pagan months as the most important months also in the newly formed 'Muslim' calendar.
These months - as well as almost every other pagan Arabian fetishes and traditions - were included in Muhammad's new Cult Belief System.
None the less, the reader should be made aware that both the Quran and Hadiths show, that Muhammad IGNORED the holiness of these months by actually ambushing and attacking the unsuspecting Quraysh caravans during these very months.
He, as usual also, excused his wanton acts of sacrilige by 'receiving' the usual MADE to ORDER'revelations'SANCTIONING his unholy actions ***
The months are:
3. Rabi' al-awwal (Rabi' I)
4. Rabi' al-thani (Rabi' II)
5. Jumada al-awwal (Jumada I)
6. Jumada al-thani (Jumada II)
11. Dhu al-Qi'dah
12. Dhu al-Hijjah
The Islamic calendar or Muslim calendar (Arabic: at-taqwim al-hijri; also called the Hijri calendar) is the calendar used to date events in many predominantly Muhammadan Muslim countries, and used by Muslims everywhere to determine the proper day on which to celebrate Islamic holy days.
It is a lunar calendar having 12 lunar months in a year of about 354 days. Because this lunar year is about 11 days shorter than the solar year, Islamic holy days, although celebrated on fixed dates in their own calendar, usually shift 11 days earlier each successive solar year, such as a year of the Gregorian calendar.
Names of the days of the week-
The Islamic week is derived from the Jewish week, as was the medieval Christian week, all of which have numbered weekdays in common. All three coincide with the Saturday through Friday planetary week.
The Islamic and Jewishweekdays begin at sunset, whereas the medieval Christian and planetary weekdays begin at the following midnight.
Muslims gather for worship at a Masjid(Mosque) at noon on Jum'a(Friday) the "gathering day", which corresponds to the sixth day of the Jewishand medieval Christian weeks, and to Friday of the planetary week.