The tonalpohualli, a Nahuatl word meaning “count of days”, is a 260-day sacred period (often termed a “year”) in use in pre-Columbian Mesoamerica, especially among the Aztecs. This calendrical period is neither solar nor lunar, but rather consists of 20 … Continue reading

The tonalpohualli, a Nahuatl word meaning “count of days”, is a 260-day sacred period (often termed a “year”) in use in pre-Columbian Mesoamerica, especially among the Aztecs. This calendrical period is neither solar nor lunar, but rather consists of 20 trecena, or 13-day periods. Each trecena is dedicated to and under the auspices of a different deity.

In part due to the sheer antiquity of the tonalpohualli, its origin is unknown. Several theories have been advanced for this unique calendrical period: that it represents a Venusian cycle, that it represents the human gestation period, or that it represents the number of days when the sun is not overhead between August 12 and April 30 in the tropical lowlands. On the other hand, some scholars including J. E. S. Thompson suggest that the tonalpohualli was not based on natural phenomenon at all, but rather on the integers 13 and 20, both considered important numbers in Mesoamerica.

The other major Aztec calendar, the xiuhpohualli, is a solar calendar, based on 18 months of 20 days. A xiuhpohualli was designated by the name of its first tonalpohualli day. For example, Hernan Cortes met Moctezuma II on the day 8 Wind in the year 1 Reed (or November 8, 1519 in the Julian calendar).

The xiuhpohualli and the tonalpohualli would coincide every 52 years. The “year” 1 Reed was the 1st in that 52 year cycle.

It is extremely unlikely that the 260-day cycle could have been based upon any natural
phenomenon that was not continuously repetitive and that was not observable in the
greater part of the area in which the sacred almanac was in use.

The nature of the 260-day cycle does not force the conclusion that it was based
upon a natural phenomenon. It could simply have resulted from the permutation of its
subcycles (13 and 20, both important numbers in Mesoamerican thought), in the same
way that the 52-year cycle resulted from the permutation of the 260-day cycle against the
solar year (4). Thus, any argument for a correspondence with some natural phenomenon
must be not merely plausible but compelling.

The earliest presently known Mesoamerican calendar system — probably (but not
unequivocally) involving a typical 260-day cycle — is that of Monte Albán I and II of
highland Oaxaca.

tonalpohualli (“count of the days”) refers to the 260-day cycle, and tonalámatl (“book of the days”) refers to the books in which it was depicted; xiuhmolpilli (“binding of the years”) was the Náhuatl word for the 52-year cycle (8). The term used by the Maya for the 260-day cycle is unknown; tzolkin, which would mean “count of the days” in Yucatec Maya, is a creation of modern Mayanists.

In the Aztec calendar, there are twenty day signs.

Nahuatl Translation
Cipactli Caiman or aquatic monster
Ehecatl Wind
Calli House
Cuetzpalin Lizard
Coatl Snake
Miquiztli Death
Mazatl Deer
Tochtli Rabbit
Atl Water
Itzcuintli Dog
Ozomahtli Monkey
Malinalli Grass
Acatl Reed
Ocelotl Ocelot or Jaguar
Cuauhtli Eagle
Cozcacuauhtli Vulture
Ollin Movement or Earthquake
Tecpatl Flint or Knife
Quiahuitl Rain
Xochitl Flower

The Xiuhpohualli (literally, year/xiuhitl-count/pohualli) 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 metztli (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 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.

The xiuhpohualli calendar, also known as the “vague year,”[citation needed] 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 xiuhpohualli 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 (in Nahuatl: ‘tonalpohualli). The Maya equivalent of the tonalpohualli 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 tonalpohualli. 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 tonalpohualli for which a festival was held. The eighteen veintena are listed below. The dates in the chart are from the early eye-witnesses, 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):

  1. Izcalli
  2. Atlcahualo or Xilomanaliztli
  3. Tlacaxipehualiztli
  4. Tozoztontli
  5. Hueytozoztli
  6. Toxcatl or Tepopochtli
  7. Etzalcualiztli
  8. Tecuilhuitontli
  9. Hueytecuilhuitl
  10. Tlaxochimaco or Miccailhuitontli
  11. Xocotlhuetzi or Hueymiccailhuitl
  12. Ochpaniztli
  13. Teotleco or Pachtontli
  14. Tepeilhiuitl or Hueypachtli
  15. Quecholli
  16. Panquetzaliztli
  17. Atemoztli
  18. Tititl

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

  • Nemontemi
Duran Time Sahagun Time Fiesta Names Symbol English Translation
1. MAR 01 – MAR 20 1. FEB 02 – FEB 21 Atlcahualo, Cuauhitlehua MetzliAtlca.jpg Ceasing of Water, Rising Trees
2. MAR 21 – APR 09 2. FEB 22 – MAR 13 Tlacaxipehualiztli MetzliTlaca.jpg Rites of Fertility; Xipe-Totec
3. APR 10 – APR 29 3. MAR 14 – APR 02 Tozoztonli ..MetzliToz.jpg Small Perforation
4. APR 30 – MAY 19 4. APR 03 – APR 22 Huey Tozotli .MetzliToz2.jpg Great Perforation
5. MAY 20 – JUN 08 5. APR 23 – MAY 12 Toxcatl ..MeztliToxcatl.jpg Dryness
6. JUN 09 – JUN 28 6. MAY 13 – JUN 01 Etzalcualiztli. MeztliEtzal.jpg Eating Maize and Beans
7. JUN 29 – JULY 18 7. JUN 02 – JUN 21 Tecuilhuitontli MeztliTecu.jpg Feast for the Revered Ones
8. JULY 19 – AUG 07 8. JUN 22 – JUL 11 Huey Tecuilhuitl MeztliHTecu.jpg Feast for the Greatly Revered Ones
9. AUG 08 – AUG 27 9. JUL 12 – JUL 31 Miccailhuitontli MeztliMicc.jpg Feast to the Revered Deceased
10. AUG 28 – SEP 16 10. AUG01 – AUG 20 Huey Miccailhuitontli MeztliMiccH.jpg Feast to the Greatly Revered Deceased
11. SEPT 17 – OCT 06 11. AUG 21 – SEPT 09 Ochpaniztli MeztliOch.jpg Sweeping and Cleaning
12. OCT 07 – OCT 26 12. SEPT10 – SEPT 29 Teotleco MeztliTeo.jpg Return of the Gods
13. OCT 27 – NOV 15 13. SEPT 30 – OCT 19 Tepeilhuitl MeztliTep.jpg Feast for the Mountains
14. NOV 16 – DEC 05 14. OCT 20 – NOV 8 Quecholli MeztliQue.jpg Precious Feather
15. DEC 06 – DEC 25 15. NOV 09 – NOV 28 Panquetzaliztli MeztliPanq.jpg Raising the Banners
16. DEC 26 – JAN 14 16. NOV 29 – DEC 18 Atemoztli MetzliAtem.jpg Descent of the Water
17. JAN 15 – FEB 03 17. DEC 19 – JAN 07 Tititl MeztliTitl.jpg Stretching for Growth
18. FEB 04 – FEB 23 18. JAN 08 – JAN 27 Izcalli MeztliIzcalli.jpg Encouragement for the Land & People
18u. FEB 24 – FEB 28 18u.JAN 28 – FEB 01 nemontemi (5 day period) MeztliNem.jpg Empty-days (nameless, undefined)

Note: Aztec years were named for the first day of the first month according to the 260-day calendar the tonalpohualli.