The Islamic world dates its calendar from the expulsion of Mohammed from Mecca and his flight to Medina in 622 CE. So 622 = year one, while 1994 = 1415. The calendar is lunar based so that the dates of festivals vary from year to year.
The spread of the festivals shown on the wheel is thus dated for 1994 when 1 Muharram (the Arabic New Year) fell on the 10th of June. By the year 2000 it will fall on the 6th of April. There are only two officially 'Islamic' festivals, ie. festivals which were suggested by the Prophet himself, as other festivals are later additions celebrating moments in his life.
In order the Arabic months run thus:
Muhurram, Safar, Rabi'I, Raba'i II, Jumada I, Jumada II, Rajab, Sha'ban, Ramadan, Shawwal, Dhu-l-Qa'da, Dhu-l-Hijja.
