This is an incomplete list of multinational festivals and holidays.
Islam
Secular and multiple religions The following festivals have no fixed date in the Gregorian calendar, and may be aligned with moon cycles or other calendars.
[16] Many religions whose holidays were formulated before the worldwide spread of the Gregorian calendar have been assigned to dates either according to their own internal religious calendar, or moon cycles, or otherwise.
Even within Christianity, Easter is a movable feast and Christmas is celebrated according to the older Julian calendar instead of the Gregorian by some sects of the religion.