Mesoamerican calendars

Mesoamerican calendars are the calendrical systems devised and used by the pre-Columbian cultures of Mesoamerica. Besides keeping time, Mesoamerican calendars were also used in religious observances and social rituals, such as for divination.

The existence of Mesoamerican calendars is known as early as ca. 500 BCE, with the essentials already appearing fully defined and functional. These calendars are still used today in the Guatemalan highlands,[2] Veracruz, Oaxaca and Chiapas, Mexico.[3]

Monte Alban Stela 12 & 13
Stelae 12 and 13 from Monte Alban, provisionally dated to 500-400 BCE, showing what is thought to be one of the earliest calendric representations in Mesoamerica.[1]

Types of calendars

Among the various calendar systems in use, two were particularly central and widespread across Mesoamerica. Common to all recorded Mesoamerican cultures, and the most important, was the 260-day calendar, a ritual calendar with no confirmed correlation to astronomical or agricultural cycles.[4] 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".[5] Because it was an approximation, over time the seasons and the true tropical year gradually "wandered" with respect to this calendar, owing to the accumulation of the differences in length. There is little hard evidence to suggest that the ancient Mesoamericans used any intercalary days to bring their calendar back into alignment. However, there is evidence to show Mesoamericans were aware of this gradual shifting, which they accounted for in other ways without amending the calendar itself.

These two 260- and 365-day calendars could also be synchronised to generate the Calendar Round, a period of 18980 days or approximately 52 years. The completion and observance of this Calendar Round sequence 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) count were used.

The use of Mesoamerican calendrics is one of the cultural traits that Paul Kirchoff used in his original formulation to define Mesoamerica as a culture area.[6] Therefore, the use of Mesoamerican calendars is specific to Mesoamerica and is not found outside its boundaries.[7]

Ritual 260-day calendar

In the 260-day cycle 20 day names pairs with 13 day numbers, totalling a cycle of 260 days. This cycle was used for divination purposes to foretell lucky and unlucky days. The date of birth was also used to give names to both humans and gods in many Mesoamerican cultures; some cultures used only the calendar name whereas others combined it with a given name. Each day sign was presided over by a god and many had associations with specific natural phenomena.


The exact origin of the 260-day count is not known, but there are several theories. One theory is that the calendar came from mathematical operations based on the numbers thirteen and twenty, which were important numbers to the Maya. The numbers multiplied together equal 260.

Another theory is that the 260-day period came from the length of human pregnancy. This is close to the average number of days between the first missed menstrual period and birth, unlike Naegele's rule which is 40 weeks (280 days) between the last menstrual period and birth. It is postulated that midwives originally developed the calendar to predict babies' expected birth dates.

A third theory comes from understanding of astronomy, geography and paleontology. The mesoamerican calendar probably originated with the Olmecs, and a settlement existed at Izapa, in southeast Chiapas Mexico, before 1200 BCE. There, at a latitude of about 15° N, the Sun passes through zenith twice a year, and there are 260 days between zenithal passages, and gnomons (used generally for observing the path of the Sun and in particular zenithal passages), were found at this and other sites. The sacred almanac may well have been set in motion on August 13, 1359 BCE, in Izapa.


In the post-classic Aztec calendar the periods of 13 days called in Spanish a trecena (no indigenous word for this period is known) were also important. The days of a trecena were usually numbered from 1 to 13. There were some exceptions, such as in the Tlapanec area where they were counted from 2 to 14.[8] The first day of the trecena, and the god who was its patron, ruled the following thirteen days. If the first day of a trecena was auspicious then so were the next twelve days.

365-day calendar

This 365-day calendar corresponded was divided into 18 'months' of 20 days each, plus 5 'nameless' days at the end of the year. The 365 day year had no leap year so it varied from the solar year by a quarter of a day each year.

The years were given their name in much the same way as the days of the 260-day calendar, 20 names were paired with 13 numbers giving 52 different possibilities for year names[9]


In the post-classic Aztec calendar the 20 days called veintenas in Spanish and meztli, meaning moon in Nahuatl, were also important.[10]

The five unlucky days

The five unlucky days were called nemontemi in Mexico. Most believe them to have come at the end of each year, but since we do not know when the year started, we cannot know for sure. We do know though, that in the Maya-area these five days (called Wayeb in Maya) were always the very last days of the year. The nemontemi were seen as 'the useless days' or the days that were dedicated to no gods, and they had prognostic power for the coming year. Therefore, People tried to do as little as possible on these days, and a person who was born during the nemontemi was considered unlucky.[11]

Calendar Round

Since both the 260-day and the 365-day calendar repeat, approximately every 52 years they reach a common end, and a new Calendar Round begins. This 52-year cycle was the most important for most Mesoamericans, with the apparent exception of the Maya elite until the end of the Classic Era, who gave equal importance to the Mesoamerican Long Count calendar.[12] According to their mythology, at the end of one of these 52-year cycles the world would be destroyed by the gods, as it had been, three times in the Popul Vuh and four times for the Aztecs. While waiting for this to happen, all fire was extinguished, house utensils were destroyed in the houses to symbolize new beginnings, people fasted and rituals were carried out. This was known as the New Fire Ceremony. When dawn broke the first day of the new cycle, torches were lit in the temples and brought out to light new fires everywhere, and ceremonies of thanksgiving were performed.[13]

Religion and calendrics

Lords of the day

In the post-classic Aztec calendar, there were 13 Lords of the Day. These were gods (and goddesses) who each represented one of the 13 days in the trecenas of the 260-day calendar. The same god always represented the same day. Quetzalcohuatl (The feathered serpent), for example, always accompanied the 9th day.

Lords of the night

There are only nine Lords of the Night, which means that they cannot always represent the same day, but the list of gods repeats itself again and again so each lord accompanies a new number each trecena. Some think that there are nine Lords of the night because they are connected to the nine levels of the underworld.[14]

Long Count

Estela C de Tres Zapotes
The back of Stela C from Tres Zapotes, an Olmec archaeological site.
This is the second oldest Long Count date yet discovered. The numerals translate to September 1, 32 BCE (Gregorian). The glyphs surrounding the date are what is thought to be one of the few surviving examples of Epi-Olmec script.

The 365-day and the 260-day calendars identified and named the days, but not the years. The combination of a solar year date and a 260-year date was enough to identify a specific date to most people's satisfaction, as such a combination did not occur again for another 52 years, above general life expectancy. To measure dates over periods longer than 52 years, the Mesoamericans devised the Long Count calendar. This calendar system was probably developed by the Olmecs and later adopted by the Maya. The use of the long count is best attested among the classic Maya, it is not known to have been used by the central Mexican cultures.

The Long Count calendar identifies a date by counting the number of days from August 11, 3114 BCE in the proleptic Gregorian calendar or September 6 3114 BCE in the Julian Calendar (-3113 astronomical). Rather than using a base-10 scheme, like Western numbering, the Long Count days were tallied in a modified base-20 scheme. Thus is equal to 25, and is equal to 40.


Long count

The correlation is based on historical, archaeological and astronomical evidence.

The commonly established way of expressing the correlation between the Maya calendar and the western calendars is to provide number of days from the start of the Julian Period (Monday, January 1, 4713 BCE) to the start of creation on 4 Ajaw, 8 Kumk'u.

The most commonly accepted correlation is the "Goodman, Martinez, Thompson" correlation (GMT correlation). The GMT correlation establishes that the creation date occurred on September 6 (Julian) or August 11 (Gregorian), 3114 BC (-3113 astronomical), Julian day number (JDN) 584283.

Maya Calendar

The Maya version of the 260-day calendar is commonly known to scholars as the Tzolkin, or Tzolk'in in the revised orthography of the Academia de Lenguas Mayas de Guatemala.[15] The Tzolk'in is combined with the 365-day calendar (known as the Haab, or Haab' ), to form a synchronized cycle lasting for 52 Haabs, called the Calendar Round. The Maya called the 5 unlucky days at the end of the year Wayeb'.

The Classic Maya, used the Long Count to record dates within periods longer than the 52 year calendar round. The post-Classic Maya used an abbreviated short count. Many Maya Long Count inscriptions also have a supplementary series which can record which one of the nine Lords of the Night rules, a Lunar series which has information about the lunar cycle, such as lunar phase and position of the Moon in a six lunation cycle and length of the current lunation and an 819-day count.

Central Mexican Calendar

Descripción histórica y cronológica de las dos piedras que con ocasión del nuevo empedrado que se está formando en la plaza principal de México, se hallaron en ella el año de 1790-1b
Image of an ancient Mexican calendar

The Central Mexican calendar system is best known in the form that was used by the Aztecs, but similar calendars were used by the Mixtecs, Zapotecs, Tlapanecs, Otomi, Matlatzinca, Totonac, Huastecs, Purépecha and at Teotihuacan. These calendars differed from the Maya version mainly in that they didn't use the long count to fix dates into a larger chronological frame than the 52-year cycle.

The Aztecs referred to the 365 and 260-day cycles as xiuhpohualli (year count) and tonalpohualli (day count) respectively. The Veintena was called metztli (moon), and the five unlucky days at the end of the solar year were called nemontemi.

Other cycles

Other calendar cycles were also recorded, such as a lunar calendar, as well as the cycles of other astronomical objects, most importantly Venus.[16]

See also


  1. ^ Marcus (1992)
  2. ^ Tedlock, Barbara, Time and the Highland Maya Revised edition (1992 Page 1) "Scores of indigenous Guatemalan communities, principally those speaking the Mayan languages known as Ixil, Mam, Pokomchí, and Quiché, keep the 260-day cycle and (in many cases) the ancient solar cycle as well (chapter 4)."
  3. ^ Miles, Susanna W, "An Analysis of the Modern Middle American Calendars: A Study in Conservation." In Acculturation in the Americas. Edited by Sol Tax, p. 273. Chicago: University of Chicago Press, 1952.
  4. ^ Miller and Taube (1993, p.48)
  5. ^ Miller and Taube (1993, p.50)
  6. ^ "Mesoamerica: Our Region". Mesoamerica. Archived from the original on 2006-10-21. Retrieved 2006-12-19. Paul Kirchhoff coined the term, Mesoamerica in 1943 from the Greek mesos or "center" and America.
  7. ^ Caso (1971, p.333)
  8. ^ Caso (1971, p.333), Edmonson (1988, p.5)
  9. ^ Hanns J. Prem, Antigua cronología Mexicana (p. 70)
  10. ^ Handbook of middleamerican indians, book 10 (pp. 339-340)
  11. ^ Broda de Casas, The Mexican Calendar (pp. 18-19)
  12. ^ Miller and Taube (1992, pp.86–88)
  13. ^ Broda de Casas, The Mexican Calendar (pp. 27-28)
  14. ^ Handbook of middleamerican indians, book 10 (pp. 335-336)
  15. ^ Refer ALMG (1988), as cited in Kettunen and Hemke (2005, p.5). This latter notes the general adoption on ALMG orthography among the Mayanist research community.
  16. ^ Balkansky (2002); Miller and Taube (1992, pp.52–54)


ALMG (Academia de Lenguas Mayas de Guatemala) (1988). Lenguas mayas de Guatemala: documento de referencia para la pronunciación de los nuevos alfabetos oficiales. ALMG Documento 1 (in Spanish). Guatemala City: Instituto Indigenista Nacional, Ministerio de Cultura y Deportes. OCLC 20330408.
Balkansky, Andrew (2002). "Zapotec Hieroglyphic Writing, by Javier Urcid Serrano [Book Review]". Antiquity. 76 (293): 904–905. doi:10.1017/S0003598X0009150X. ISSN 0003-598X. OCLC 1481624. Retrieved 2006-10-20.
Caso, Alfonso (1971). "Calendrical Systems of Central Mexico". In Gordon F. Ekholm and Ignacio Bernal (Volume eds.) (ed.). Handbook of Middle American Indians, Vol. 10: Archaeology of Northern Mesoamerica, part I. R. Wauchope (General Editor). Austin: University of Texas Press. pp. 333–348. ISBN 978-0-292-70150-2. OCLC 277126.
Coe, Michael D. (1987). The Maya. Ancient peoples and places series (4th edition (revised) ed.). London and New York: Thames & Hudson. ISBN 978-0-500-27455-2. OCLC 15895415.
Edmonson, Munro S. (1988). The Book of the Year: Middle American Calendrical Systems. Salt Lake City: University of Utah Press. ISBN 978-0-87480-288-7. OCLC 17650412.
Hassig, Ross (2001). Time, History, and Belief in Aztec and Colonial Mexico. Austin: University of Texas Press. ISBN 978-0-292-73139-4. OCLC 44167649.
Kettunen, Harri; Christophe Helmke (2005). Introduction to Maya Hieroglyphs (PDF online publication). Wayeb and Leiden University. Retrieved 2008-08-07.
Marcus, Joyce (1992). Mesoamerican Writing Systems: Propaganda, Myth, and History in Four Ancient Civilizations. Princeton, NJ: Princeton University Press. ISBN 978-0-691-09474-8. OCLC 25549355.
Malmström, Vincent H. (September 17, 1973). "Origin of the Mesoamerican 260-Day Calendar" (PDF Reprinted). Science. 181 (4103): 939–941. Bibcode:1973Sci...181..939M. CiteSeerX doi:10.1126/science.181.4103.939. PMID 17835843.
Miller, Mary; Karl Taube (1993). The Gods and Symbols of Ancient Mexico and the Maya: An Illustrated Dictionary of Mesoamerican Religion. London: Thames & Hudson. ISBN 978-0-500-05068-2. OCLC 27667317.
Nowotny, Karl Anton (2005). Tlacuilolli: style and contents of the Mexican pictorial manuscripts with a catalog of the Borgia Group. George A. Everett, Jr. and Edward B. Sisson (trans. and eds.), with a foreword by Ferdinand Anders. Norman: University of Oklahoma Press. ISBN 978-0-8061-3653-0. OCLC 56527102.

External links

365-day calendar

A 365-day calendar consists of exactly 365 days per year (no leap days), and is primarily used in computer models and as an assumption in every-day calculations. For example, a calculation of a daily rate may use an annual total divided by exactly 365.

Interest rates in some banks are calculated using a 365-day calendar.

Aztec calendar

The Aztec or Mexica calendar is the calendar system that was used by the Aztecs as well as other Pre-Columbian peoples of central Mexico. It is one of the Mesoamerican calendars, sharing the basic structure of calendars from throughout ancient Mesoamerica.

The calendar consisted of a 365-day calendar cycle called xiuhpōhualli (year count) and a 260-day ritual cycle called tōnalpōhualli (day count). These two cycles together formed a 52-year "century", sometimes called the "calendar round". The xiuhpōhualli is considered to be the agricultural calendar, since it is based on the sun, and the tōnalpōhualli is considered to be the sacred calendar...

Culture of El Salvador

The culture of El Salvador is a Central American culture nation influenced by the clash of ancient Mesoamerica and medieval Iberian Peninsula. Salvadoran culture is influenced by Native American culture (Lenca people, Cacaopera people, Maya peoples, Pipil people) as well as Latin American culture (Latin America, Hispanic America, Ibero-America). Mestizo culture and the Catholic Church dominates the country. Although the Romance language, Castilian Spanish, is the official and dominant language spoken in El Salvador, Salvadoran Spanish which is part of Central American Spanish has influences of Native American languages of El Salvador such as Lencan languages, Cacaopera language, Mayan languages and Pipil language, which are still spoken in some regions of El Salvador.

Karl Anton Nowotny

Karl Anton Nowotny (June 21, 1904, Hollabrunn – December 31, 1978, Vienna) was an Austrian ethnographer, art historian and academic, specialising in the study of Mesoamerican cultures. He is most renowned for his analyses and reproductions of Mesoamerican codices, and his commentaries on their iconography and symbolisms.

Nowotny was a pioneer and leading exponent of applying comparative ethnography to the study of pre-Columbian and conques-era texts and codices. In this technique, the meaning and symbolism of the texts are analysed and compared with the cultural practices and beliefs of modern indigenous Mesoamerican peoples whose traditions have been maintained. Nowotny used comprehensive ethnographic studies—such as those conducted by Leonhard Schultze in the 1930s among the Nahuas of the central Mexican altiplano—as a means of garnering further insight into the ancestral practices and beliefs underpinning the codices and related iconographies.Nowotny also contributed extensively to the study and interpretation of pre-Columbian Mesoamerican calendars, their functioning and how they were used. Building upon work by earlier scholars such as Eduard Seler, Nowotny and his contemporaries like Alfonso Caso and Paul Kirchhoff greatly added to the scholarly understanding of calendrical elements such as the central Mexican tonalpohualli, veintena and trecena cycles. Nowotny's analysis and exposition of the ritual and divinatory importance of the tonalamatl almanac has been regarded as of "critical importance" to the modern understanding of this almanac, and a significant development beyond the primarily astronomically based approach of Seler and other predecessors.

List of calendars

This is a list of calendars. Included are historical calendars as well as proposed ones. Historical calendars are often grouped into larger categories by cultural sphere or historical period; thus O'Neil (1976) distinguishes the groupings Egyptian calendars (Ancient Egypt), Babylonian calendars (Ancient Mesopotamia), Indian calendars (Hindu and Buddhist traditions of the Indian subcontinent), Chinese calendars and Mesoamerican calendars.

These are not specific calendars but series of historical calendars undergoing reforms or regional diversification.

In Classical Antiquity, the Hellenic calendars inspired the Roman calendar, including the solar Julian calendar introduced in 45 BC. Many modern calendar proposals, including the Gregorian calendar itself, are in turn modifications of the Julian calendar.

List of cycles

This is a list of recurring cycles. See also Index of wave articles, Time, and Pattern.

Lords of the Day

In Aztec mythology the Lords of the Day (Classical Nahuatl: Tonalteuctin) are a set of thirteen gods that ruled over a particular day corresponding to one of the thirteen heavens. They were cyclical, so that same god recurred every thirteen days. In the Aztec calendar, the lords of the day are

Xiuhtecuhtli, god of fire and time.

Tlaltecuhtli, god of the earth.

Chalchiuhtlicue, goddess of water, lakes, rivers, seas, streams, horizontal waters, storms and baptism.

Tonatiuh, god of the sun.

Tlazolteotl, goddess of lust, carnality, sexual misdeeds.

Mictlantecuhtli, god of the underworld.

Centeotl, goddess of maize. Also recognized as Chicomecoatl, goddess of agriculture.

Tlaloc, god of the thunder, rain and earthquakes.

Quetzalcoatl, god of wisdom, life, knowledge, morning star, fertility, patron of the winds and the light, the lord of the West.

Tezcatlipoca, god of providence, matter and the invisible, ruler of the night, Great Bear, impalpable, ubiquity and the twilight, the lord of the North.

Mictecacihuatl, goddess of the underworld.

Tlahuizcalpantecuhtli, god of dawn.

Citlalicue, goddess of the female stars (Milky Way).

Lords of the Night

In Mesoamerican mythology the Lords of the Night (Classical Nahuatl: Yoalteuctin) are a set of nine gods who each ruled over every ninth night forming a calendrical cycle. Each lord was associated with a particular fortune, bad or good, that was an omen for the night that they ruled over.The lords of the night are known in both the Aztec and Maya calendar, although the specific names of the Maya Night Lords are unknown.The glyphs corresponding to the night gods are known and mayanists identify them with labels G1 to G9, the G series. Generally, these glyphs are frequently used with a fixed glyph coined F. The only Mayan light lord that has been identified is the God G9,Pauahtun the Aged Quadripartite God.The existence of a 9 nights cycle in Mesoamerican calendrics was first discovered in 1904 by Eduard Seler. The Aztec names of the Deities are known because their names are glossed in the Codex Telleriano-Remensis and Codex Tudela. Seler argued that the 9 lords each corresponded to one of the nine levels of the under world and ruled the corresponding hour of the night time, this argument has not generally been accepted, since the evidence suggests that the lord of a given night ruled over that entire night. Zelia Nuttall argued that the Nine Lords of the Night represented the nine moons of the Lunar year. The cycle of the Nine Lords of the Night held special relation to the Mesoamerican ritual calendar of 260-days and nights or -night which includes exactly 29 groups of 9 nights each, and also, approximately, 9 vague lunations of 29 days each.

The Nine Lords of the Night in Aztec mythology are:

Xiuhtecuhtli ("Turquoise/Year/Fire Lord")

Tezcatlipoca ("Smoking Mirror")

Piltzintecuhtli ("Prince Lord")

Centeotl ("Maize God")

Mictlantecuhtli ("Underworld Lord")

Chalchiuhtlicue ("Jade Is Her Skirt")

Tlazolteotl ("Filth God[dess]")

Tepeyollotl ("Mountain Heart")

Tlaloc (Rain God)

Marie Brennan

Marie Brennan is the pseudonym of Bryn Neuenschwander, an American fantasy author. Her works include the Doppelganger duology (Doppelganger and its sequel Warrior and Witch, respectively retitled Warrior and Witch on later printings); the Onyx Court series; the Memoirs of Lady Trent series; and numerous short stories. The first of the Onyx Court novels, Midnight Never Come, published on 1 May 2008 in the United Kingdom, and 1 June 2008 in the United States, received a four star-review from SFX Magazine.As an undergraduate at Harvard University, Neuenschwander served as co-chair of the Harvard-Radcliffe Science Fiction Association. After graduating from Harvard, she pursued graduate studies at Indiana University, studying folklore and anthropology; in 2008 she left graduate school without completing her PhD, in order to pursue writing full-time.

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.

Mesoamerican world tree

World trees are a prevalent motif occurring in the mythical cosmologies, creation accounts, and iconographies of the pre-Columbian cultures of Mesoamerica. In the Mesoamerican context, world trees embodied the four cardinal directions, which also serve to represent the fourfold nature of a central world tree, a symbolic axis mundi which connects the planes of the Underworld and the sky with that of the terrestrial realm.Depictions of world trees, both in their directional and central aspects, are found in the art and mythological traditions of cultures such as the Maya, Aztec, Izapan, Mixtec, Olmec, and others, dating to at least the Mid/Late Formative periods of Mesoamerican chronology. Among the Maya, the central world tree was conceived as or represented by a ceiba tree, and is known variously as a wacah chan or yax imix che, depending on the Mayan language. The trunk of the tree could also be represented by an upright caiman, whose skin evokes the tree's spiny trunk.Directional world trees are also associated with the four Yearbearers in Mesoamerican calendars, and the directional colors and deities. Mesoamerican codices which have this association outlined include the Dresden, Borgia and Fejérváry-Mayer codices. It is supposed that Mesoamerican sites and ceremonial centers frequently had actual trees planted at each of the four cardinal directions, representing the quadripartite concept.Izapa Stela 5 is considered a possible representation of a World Tree.

World trees are frequently depicted with birds in their branches, and their roots extending into earth or water (sometimes atop a "water-monster", symbolic of the underworld).

The central world tree has also been interpreted as a representation of the band of the Milky Way.

Mixtec writing

Mixtec writing originated as a logographic writing system during the Post-Classic period in Mesoamerican history. Records of genealogy, historic events, and myths are found in the pre-Columbian Mixtec codices. The arrival of Europeans in 1520 AD caused changes in form, style, and the function of the Mixtec writings. Today these codices and other Mixtec writings are used as a source of ethnographic, linguistic, and historical information for scholars, and help to preserve the identity of the Mixtec people as migration and globalization introduce new cultural influences.


A trecena is a 13-day period used in pre-Columbian Mesoamerican calendars. The 260-day calendar (the tonalpohualli) was divided into 20 trecenas. Trecena is derived from the Spanish chroniclers and translates to "a group of thirteen" in the same way that a dozen (or in Spanish docena) relates to the number twelve. It is associated with the Aztecs, but is called different names in the calendars of the Maya, Zapotec, Mixtec, and others of the region.

Many surviving Mesoamerican codices, such as Codex Borbonicus, are divinitory calendars, based on the 260-day year, with each page representing one trecena.

Tree of life

The tree of life is a widespread myth (mytheme) or archetype in the world's mythologies, related to the concept of sacred tree more generally, and hence in religious and philosophical tradition.

The tree of knowledge, connecting to heaven and the underworld, and the tree of life, connecting all forms of creation, are both forms of the world tree or cosmic tree, and are portrayed in various religions and philosophies as the same tree.


Tzolkʼin (Mayan pronunciation: [t͡sol ˈkʼin], formerly and commonly tzolkin) is the name bestowed by Mayanists on the 260-day Mesoamerican calendar originated by the Maya civilization of pre-Columbian Mesoamerica.

The tzolkʼin, the basic cycle of the Maya calendar, is a preeminent component in the society and rituals of the ancient and the modern Maya. The tzolkʼin is still in use by several Maya communities in the Guatemalan highlands. Its use is marginal but spreading in this region, although opposition from Evangelical Christian converts continues in some communities.

The word tzolkʼin, meaning "division of days", is a western coinage in Yukatek Maya. There are various terms in actual use in the languages of Maya groups who have maintained an unbroken count for over 500 years: The Kʼicheʼ use the term Aj Ilabal Qʼij [aχ ilaɓal ʠiχ] or Rajilabal Kʼij [ɾaχ ilaɓal ʠiχ], 'the sense of the day' or 'the round of the days' and the Kaqchikel use the term Chol Qʼij [tʃol ʠiχ], 'the organization of time'. The names of this calendar as used by the pre-Columbian Maya are not widely known. The corresponding Postclassic Aztec calendar, was called tonalpohualli, in the Nahuatl language.


A veintena is the Spanish-derived name for a 20-day period used in pre-Columbian Mesoamerican calendars. The division is often casually referred to as a "month", although it is not coordinated with the lunar cycle. The term is most frequently used with respect to the 365-day Aztec calendar, the xiuhpohualli, although 20-day periods are also used in the 365-day Maya calendar (the Mayan tun), as well as by other Mesoamerican civilizations such as the Zapotec and Mixtec.

The 365-day cycle is divided into 18 veintenas of 20 days each, giving 360 days; an additional 5 "nameless days" or nemontemi are appended to bring the total to 365.The name used for these periods in pre-Columbian times is unknown. In Nahuatl, the word for "twenty days" is cempōhualilhuitl [sempoːwalˈilwit͡ɬ] from the words cempōhualli [sempoːˈwalːi] "twenty" and ilhuitl [ˈilwit͡ɬ] "day". Through Spanish usage, the 20-day period of the Aztec calendar has become commonly known as a veintena. The Aztec word for moon is metztli, and this word is today to describe these 20-day periods, although as the sixteenth-century missionary and early ethnographer, Diego Durán explained:

In ancient times the year was composed of eighteen months, and thus it was observed by these Indian people. Since their months were made of no more than twenty days, these were all the days contained in a month, because they were not guided by the moon but by the days; therefore, the year had eighteen months. The days of the year were counted twenty by twenty.

Each 20-day period started on a Cipactli (Crocodile) day of the tonalpohualli for which a festival was held. The eighteen veintena are listed below. The dates in the chart are from the early eyewitnesses, Diego Durán and Bernardino de Sahagún. Each wrote what they learned from Nahua informants. Sahagún's date precedes the Durán's observations by several decades and is believed to be more recent to the Aztec surrender to the Spanish. Both are shown to emphasize the fact that the beginning of the Native new year became non-uniform as a result of an absence of the unifying force of Tenochtitlan after the Mexica defeat.


A week is a time unit equal to seven days. It is the standard time period used for cycles of rest days in most parts of the world, mostly alongside—although not strictly part of—the Gregorian calendar.

In many languages, the days of the week are named after classical planets or gods of a pantheon. In English, the names are Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday.

ISO 8601 includes the ISO week date system, a numbering system for weeks within a given year – each week begins on a Monday and is associated with the year that contains that week's Thursday (so that if a year starts in a long weekend Friday–Sunday, week number one of the year will start after that). ISO 8601 assigns numbers to the days of the week, running from 1 to 7 for Monday through to Sunday.

The term "week" is sometimes expanded to refer to other time units comprising a few days, such as the nundinal cycle of the ancient Roman calendar, the "work week", or "school week" referring only to the days spent on those activities.

World tree

The world tree is a motif present in several religions and mythologies, particularly Indo-European religions, Siberian religions, and Native American religions. The world tree is represented as a colossal tree which supports the heavens, thereby connecting the heavens, the terrestrial world, and, through its roots, the underworld. It may also be strongly connected to the motif of the tree of life, but it is the source of wisdom of the ages.

Specific world trees include égig érő fa in Hungarian mythology, Ağaç Ana in Turkic mythology, Modun in Mongol mythology, Yggdrasil (or Irminsul) in Norse (including Germanic) mythology, the oak in Slavic, Finnish and Baltic, Iroko in Yoruba religion, Jianmu in Chinese mythology, and in Hindu mythology the Ashvattha (a Ficus religiosa).


The Xiuhpōhualli (Nahuatl pronunciation: [ʃiwpoːˈwalːi], from xihuitl + pōhualli) was a 365-day calendar used by the Aztecs and other pre-Columbian Nahua peoples in central Mexico. It was composed of eighteen 20-day "months," called veintenas or mētztli (the contemporary Nahuatl word for month) with a separate 5-day period at the end of the year called the nemontemi. Whatever name that was used for these periods in pre-Columbian times is unknown. Through Spanish usage, the 20-day period of the Aztec calendar has become commonly known as a veintena. The Aztec word for moon is mētztli, and this word is today to describe these 20-day periods, although as the sixteenth-century missionary and early ethnographer, Diego Durán explained:

In ancient times the year was composed of eighteen months, and thus it was observed by these Indian people. Since their months were made of no more than twenty days, these were all the days contained in a month, because they were not guided by the moon but by the days; therefore, the year had eighteen months. The days of the year were counted twenty by twenty.

The xiuhpōhualli calendar, (in history known as the "vague year" which means no leap day) had its antecedents in form and function in earlier Mesoamerican calendars, and the 365-day count has a long history of use throughout the region. The Maya civilization version of the xiuhpōhualli is known as the haab', and 20-days period was the uinal. The Maya equivalent of nemontemi is wayeb'. In common with other Mesoamerican cultures the Aztecs also used a separate 260-day calendar (Classical Nahuatl: tonalpōhualli). The Maya equivalent of the tonalpōhualli is the tzolk'in. Together, these calendars would coincide once every 52 years, the so-called "calendar round," which was initiated by a New Fire ceremony.

Aztec years were named for the last day of the 18th month according to the 260-day calendar the tonalpōhualli. The first year of the Aztec calendar round was called 2 Acatl and the last 1 Tochtli. The solar calendar was connected to agricultural practices and held an important place in Aztec religion, with each month being associated with its own particular religious and agricultural festivals.

Each 20-day period started on a Cipactli (Crocodile) day of the tonalpōhualli for which a festival was held. The eighteen veintena are listed below. The dates in the chart are from the early eyewitnesses, Diego Durán and Bernardino de Sahagún. Each wrote what they learned from Nahua informants. Sahagún's date precedes the Durán's observations by several decades and is believed to be more recent to the Aztec surrender to the Spanish. Both are shown to emphasize the fact that the beginning of the Native new year became non-uniform as a result of an absence of the unifying force of Tenochtitlan after the Mexica defeat.

The 20-day months (veintenas) of the Aztec solar calendar were called (in two sequences):


Atlcahualo or Xilomanaliztli




Toxcatl or Tepopochtli




Tlaxochimaco or Miccailhuitontli

Xocotlhuetzi or Hueymiccailhuitl


Teotleco or Pachtontli

Tepeilhuitl or Hueypachtli




TititlThe five days inserted at the end of a year and which were considered unlucky:

NemontemiNote: Aztec years were named for the last day of their fourth month according to the 260-day calendar, the tonalpohualli.

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