[2] 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 BC.
[3] By the Maya mythological tradition, as documented in Colonial Yucatec accounts and reconstructed from Late Classic and Postclassic inscriptions, the deity Itzamna is frequently credited with bringing the knowledge of the calendrical system to the ancestral Maya, along with writing in general and other foundational aspects of Mayan culture.
[8] By its linear nature, the Long Count was capable of being extended to refer to any date far into the past or future.
Less-prevalent or poorly understood cycles, combinations and calendar progressions were also tracked.
Repeating sets of 9 days (see below "Nine lords of the night")[9] associated with different groups of deities, animals and other significant concepts are also known.
The word tzolkʼin is a neologism coined in Yucatec Maya, to mean "count of days" (Coe 1992).
The earliest known inscription with a Tzolkʼin is an Olmec earspool with 2 Ahau 3 Ceh - 6.3.10.9.0, September 2, -678 (Julian astronomical).
Foster (2002) writes, "During Wayeb, portals between the mortal realm and the Underworld dissolved.
To ward off these evil spirits, the Maya had customs and rituals they practiced during Wayebʼ.
For example, people avoided leaving their houses and washing or combing their hair.
Bricker (1982) estimates that the Haabʼ was first used around 550 BC with a starting point of the winter solstice.
[21] Moreover, since the Year Bearers are geographically identified with boundary markers or mountains, they help define the local community.
[22] The classic system of Year Bearers described above is found at Tikal and in the Dresden Codex.
During the Late Classic period a different set of Year Bearers was in use in Campeche.
In this system the Year Bearers were the days that coincided with 2 Pop: Kʼan, Muluc, Ix and Kawak.
In addition, just before the Spanish conquest in Mayapan the Maya began to number the days of the Haabʼ from 1 to 20.
The Classic Year Bearer system is still in use in the Guatemalan highlands[23] and in Veracruz, Oaxaca and Chiapas, Mexico.
[24] Since Calendar Round dates repeat every 18,980 days, approximately 52 solar years, the cycle repeats roughly once each lifetime, so a more refined method of dating was needed if history was to be recorded accurately.
To specify dates over periods longer than 52 years, Mesoamericans used the Long Count calendar.
Misinterpretation of the Mesoamerican Long Count calendar was the basis for a popular belief that a cataclysm would take place on December 21, 2012.
The date of the start of the next piktun (a complete series of 20 bʼakʼtuns), at Long Count 1.0.0.0.0.0, is October 13, 4772.
The Supplementary Series most commonly consists of the following elements: Each night was ruled by one of the nine lords of the underworld.
[30] Some Mayan monuments include glyphs that record an 819-day count[31] in their Initial Series.
[34] Each group of 819 days was associated with one of four colors and the cardinal direction with which it was associated – black corresponded to west, red to east, white to north and yellow to south.
That is, starting with the katun that begins with 1 Imix, the sequence of concluding day numbers is 11, 9, 7, 5, 3, 1, 12, 10, 8, 6, 4, 2, 13, 11, ..., all named Ahau.
In characteristic Mesoamerican fashion, these books project the cycle onto the landscape, with 13 Ahauob 'Lordships' dividing the land of Yucatán into 13 'kingdoms'.