Mesoamerican Long Count calendar Mesoamerican Long Count calendar The Mesoamerican Long Count calendar is a non-repeating, vigesimal (base-20) and base-18 calendar used by several pre-Columbian Mesoamerican cultures, most notably the Maya. For this reason, it is often known as the Maya (or Mayan) Long Count calendar. Using a modified vigesimal tally, the Long Count calendar identifies a day by counting the number of days passed since a mythical creation date that corresponds to August 11, 3114 BCE in the Proleptic Gregorian calendar. The Long Count calendar was widely used on monuments. The two most widely used calendars in pre-Columbian Mesoamerica, were the 260-day Tzolk'in
Mesoamerican calendars calendar, a ritual calendar with no confirmed correlation to astronomical or agricultural cycles. Apparently the earliest Mesoamerican calendar to be developed, it was known by a variety of local terms, and its named components and the glyphs used to depict them were similarly culture-specific. However, it is clear that this calendar functioned in essentially the same way across cultures, and down through the chronological periods it was maintained. The second of the major calendars was one representing a 365-day period approximating the tropical year, known sometimes as the "vague year". Because it was an approximation, over time the seasons and