The Aztec Calendar Systems.

The first page of the ritual almanac, the Codex Fejervary-Mayer.(Townsend 1994:125)

"In Mesoamerican thought, the calendar concerned the definition and ordering of space as well as time [and] played an essential role in mythology as well as in daily life."


The Mesoamericans had long since 'computed time' and although each 'calendar' would differ from region to region, they were fundamentally the same. The Aztecs 'counted time' in two different ways; the tonalpohuahalli , or, 'counting of the days', which was a 260 day cycle, and the xiuhpohualli, or 'counting of the years', which was a 365 day solar count. The tonalpohuahalli was a sacred almanac of days and was used for divination purposes. This was an ancient form of calendar which possibly dates back to the Olmec period in the first millenium b.c.

The Tonalpohualli

It is possible that the tonalpohualli is based on actual astronomical observations since, according to archaeoastronomers, the sun crosses a zenith point over Copan (the classic Maya city) precisely every 260 days. The structure of such cities and temples in alignment with the sun and moon, and the consequent influence this had on the regulation of planting and harvesting and also religious festivals, has led archaeoastronmers to decipher and place Aztec astronomy within its greater context and influence, for example, within the calendrical system.

The 260 day cycle of the tonalpohualli was organised into 20 days, each of which were given a special patron, hieroglyph and number.

As is represented in the schematic representation below, these days interlocked and rotated with the numbers 1 to 13 which were in turn symbolised by the appropriate number of dots.

Schematic representation of the 260 day tonalpohualli calendar. The 20 named days articulate with the numbers 1 to 13.

As the interlocking scheme of numbers and days progressed, so a new combination of day names would occur. Each 260 day cycle comprised of 20 'weeks' of 13 days. Each 'week' started at the number 1 and the next day-name in sequential order within the rotation.

The tonalpohualli is further divisible by the numbers 2,4 and 5. It is improbable that the period of 130 days (260 divided by 2) had any ritual significance. However, when divided by 4, (giving a period of 65 days), the calendar reveals the important cocijos of the Zapotec Calendar. Most important however is the division of the calendar by 5, giving a period of 52 days; the Aztec century. The 5 consequent centuries are also important as they may correspond to division of the universe; the four directions and the centre. The tonalpohualli also appears to have been divided into other combinations, each significant for example astronomically or in determining the future and lucky and unlucky days.

The full cycle would therefore take a period of 260 days; 20 x 13 = 260. According to this arrangement, each day was unique not only in its combination, but in the minimal chance of it reoccurring. The days and weeks of the Aztecs therefore not only cyclical, but given special intrinsic meanings.

In addition, each day and night was presided over by 13 Lords of the day and nine Lords of the Night each with an associated glyph. It is most likely that the thirteen Lords of the Day corresponded to the thirteen heavens and that the nine Lords of the Night corresponded to the nine hells. The thirteen Lords of the Day were;

Five of these 13 Gods presided over the five cosmogenic suns, these were; Tezcatlipoca, Quetzalcoatl, Tlaloc, Chalchiutlicue, and Tonatiuh.

The nine Lords of the Night were;

Finally, specific colours, animals and cardinal points were attributed to the tonalpohualli as follows:

Direction: East North West South
Colour: yellow red white blue
Glyph: eagle tiger snake rabbit
Year: Acatl Tecpatl Calli Tochtli
Gods: Tonatiuh and
or Yahauqui
Quetzalcoatl or
and the Yellow or
White Tezcatlipoca
Huitzilopochtli, ie,
Blue Tezcatlipoca

"Mesoamerican calendrical systems were not simply used to delineate thirteen-day weeks, twenty-day months, vague years and other periods of daily reality. They also distinguished intervals that were especially charged with sacred and often dangerous powers. The peoples of ancient Mesoamerica keenly observed the sky and used the calendar to predict solar and lunar eclipses, the cycles of the planet Venus, the apparent movements of constellations and other celestial events. To them, these occurrences were not the mechanical movements of innate celestial bodies but constituted the activities of gods, the actual recapitulation of mythical events from the time of creation. In central Mexico, the first appearance of Venus as the Morning Star was Tlahuizcalpantecuhtli, Lord of the Dawn, who battled the rising sun at the first dawning at Teotihuacan. The calendrical cycles themselves also delineated sacred moments of time. The completion of the Aztec fifty-two year cycle was marked by an anxious vigil: if new fire was not successfully drilled, the terrifying star demons of darkness, the tzitzimime, would reassert their control over the world."


A detail from the Codex Borbonicus;
the most famous of the screenfold books.

Screenfold books called tonalamatls or 'paper or book of days' held the tonalpohuahalli counts. Each intricately decorated book was interpreted by professional diviners who gave advice and wisdom to all. For example, they predicted the future for newly born children and also farmers and their crops, illustrating the way in which religion and the calendar affected ritual and daily life. These screenfold books and also the writings of the Spanish illuminate this to a greater degree:

These characters [of the tonalamatls] also taught the Indian nations the days on which they were to sow, reap, till the land, cultivate corn, weed, harvest, store, shell the ears of corn, sow beans and flax seed. They always took into account that it had to be done in such and such month, after such and such feast, on such and such day, under such and such a sign. All this was done with superstitious order and care. If chili was not sown on a certain day, aquash on another, maize on another, and so forth, in disregard of the orderly count of the days, the people felt there would be great damage and loss of any crop sown outside of the established order of the days. The reason for all this was that some signs were held to be good, others evil, and others indifferent, just as our almanacs record the signs of the zodiac."

(Townsend 1994:125)

This quote also illustrates the Aztec's use of divination and belief in omens, and the extent to which it ordered and ruled their everyday and spiritual lives. Needless to say, these methods of predicting the future were also deeply entrenched in the political and religious stratas of society and were used to decisions on all levels of importance and at all levels of society. This may be further exemplified by the xiuhpohualli, or 360 day count.

The xiuhpohualli

The xiuhpohualli dictated the annual ceremonial calendar of the Aztec state. This calendar was divided into eighteen 'months' of twenty days with the dangerous five day nemontemi which divided the old year from the new. Each month was celebrated with a festival, as was the beginning and end of each fifty-two year cycle when the 'binding of the years' took place. This entailed tying up fifty-two reeds, the xiuhmopilli, which represented each year. Further,the end of two cycles was particular cause for celebration since it was at this time that the tonalpohualli and the fifty-two year cycle occurred simultaneously.

Intrinsic to an understanding of the Aztec Calendar systems is the Aztec concept of cyclical time

The Stone:Discovery
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Clickable Calendar Stone
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