Mesoamerican calendars was of ritual significance to a number of Mesoamerican cultures. A third major calendar form known as the Long Count is found in the inscriptions of several Mesoamerican cultures, most famously those of the Maya civilization who developed it to its fullest extent during the Classic period (ca. 200–900 CE). The Long Count provided the ability to uniquely identify days over a much longer period of time, by combining a sequence of day-counts or cycles of increasing length, calculated or set from a particular date in the mythical past. Most commonly, five such higher-order cycles in a modified vigesimal (base-20)
Adoption of the Gregorian calendar No. 28 of Month 1 () On the other hand, people never call dates on the Chinese calendar as "No. "dd".", which avoids any possible ambiguity. When referencing dates before the introduction of the Gregorian calendar in 1582, the official Chinese calendar may either inherit the issues with earlier calendars to be historically correct or follow the proleptic Gregorian calendar if so specified. The Islamic calendar is a lunar one, so that there are twelve lunar months in a year of 354 or 355 days, being 11 days shorter than a solar year. Consequently, holy days in Islam migrate around