Islamic holidays are based on the lunar calendar and
they vary by a few days every year. The two official Muslim holidays are
Eid-al-Adha, the Feast of Sacrifice and Eid-al-Fitr, the end
of Ramadan. Other holidays such as Mawled, the birth of the Prophet,
Lyalat al-Isra, the ascension of the prophet, and Muharram,
the Muslim New Year, are celebrated individually as a matter of personal
The Islamic calendar is based on the beginning of the Islamic era, the year of Hijrah, during which the Prophet Mohammed emigrated from Mecca to Medina. The prophet's departure occurred on July 16, 622 A.D. Hijrah years are lunar; one month is the cycle between the two moons. Every 32 Gregorian solar years, which is the method used in the western world, are approximately equal to 33 Muslim lunar years.
National Day is observed on September 23 each year to mark the unification of the Kingdom of Saudi Arabia into one state.