Abstract: The invention relates to an Islamic Hijiri calendar for a mechanical clockwork movement comprising a 30-position date indicator arranged to be driven by a date-driving mechanism and to engage with a large rocker (7). A month control mechanism is arranged to differentiate between the months with 29 days and those with 30 days. A year control mechanism is arranged to differentiate between an abundant year and a common year. During a common year, a large rocker (7) is arranged to engage with a date star (9), to move two teeth of the date star (9) in order to move from the 29th of a month to the 1 st of the following month, the large rocker (7) resting on the month cam (4).