Maya calendar Maya calendar The Maya calendar is a system of calendars used in pre-Columbian Mesoamerica and in many modern communities in the Guatemalan highlands, Veracruz, Oaxaca and Chiapas, Mexico. The essentials of the Maya calendar are based upon a system which had been in common use throughout the region, dating back to at least the 5th century BCE. It shares many aspects with calendars employed by other earlier Mesoamerican civilizations, such as the Zapotec and Olmec and contemporary or later ones such as the Mixtec and Aztec calendars. By the Maya mythological tradition, as documented in Colonial Yucatec accounts and reconstructed
Adoption of the Gregorian calendar to use their own calendars, which usually result in fixed dates being celebrated in accordance with the Julian calendar. This is most interesting in the case of the Syriac Orthodox Church, as one of its Patriarchs Ignatius Nemet Allah I was one of the nine scholars who devised the Gregorian calendar. The Indian Orthodox Church uses the Gregorian calendar along with their autonomous Syriac Orthodox counterparts in India, the Malankara Jacobite Syriac Orthodox Church. The Armenian Apostolic Church adopted the Gregorian calendar in 1923, except in the Armenian Patriarchate of Jerusalem, where the old Julian calendar is still in use.