Tōnalpōhualli

The tonalpohualli Nahuatl pronunciation: [toːnaɬpoːˈwalːi], a Nahuatl word meaning "count of days", is an Aztec version of the 260-day calendar in use in pre-Columbian Mesoamerica. This calendar is neither solar nor lunar, but rather consists of 20 (veintenas), 13-day (trecenas) periods. Each trecena is ruled by a different deity.

Description

The basis of the tonalpohualli, is unknown. Several theories have been advanced for this calendrical period: that it represents a Venusian cycle, that it represents the human gestation period, or that it represents the number of days between the zenithal passage of the sun in the tropical lowlands. On the other hand, some scholars including J. E. S. Thompson suggest that the tonalpohualli was not based on natural phenomena 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 365-day year, based on 18 months of 20 days and five nameless days. A xiuhpohualli was designated by the name of its first tonalpohualli day. For example, Hernán Cortés met Moctezuma II on the day 8 Wind in the year 1 Reed^{[citation needed]} (or November 8, 1519 in the Julian calendar^[1]).

The xiuhpohualli and the tonalpohualli would coincide approximately every 52 years.

Day signs

^{[citation needed]}

n.º	Trecena	Aztec deities associated	Cardinal point
1	1 Cipactli (Caiman or aquatic monster)	Tonacatecuhtli	East
2	1 Ehēcatl (Wind)	Quetzalcoatl	North
3	1 Calli (House)	Tepeyollotl, Quetzalcoatl	West
4	1 Cuetzpalin (Lizard)	Huehuecoyotl or Macuilxochitl	South
5	1 Cōātl (Snake)	Chalchiuhtlicue and Tlazolteotl	East
6	1 Miquiztli (Death)	Tonatiuh and Tecuciztecatl	North
7	1 Mazātl (Deer)	Tlaloc and Chicomecoatl o 4 Ehécatl	West
8	1 Tōchtli (Rabbit)	Mayahuel and Xochipilli or Cinteotl	South
9	1 Ātl (Water)	Tlahuizcalpantecuhtli or Xiuhtecuhtli	East
10	1 Itzcuintli (Dog)	Mictlantecuhtli	North
11	1 Ozomahtli (Monkey)	Patecatl and Cuauhtliocelotl	West
12	1 Malīnalli (Grass)	Itztlacoliuhqui	South
13	1 Ācatl (Reed)	Tezcatlipoca or Uactli and Ixcuina or Tlazolteotl	East
14	1 Ocēlōtl (Ocelot or Jaguar)	Tlazolteotl	North
15	1 Cuāuhtli (Eagle)	Xipe Totec and Quetzalcoatl	West
16	1 Cōzcacuāuhtli (Vulture)	Itzpapalotl	South
17	1 Ōlīn (Movement or Earthquake)	Xolotl and Tlalchitonatiuh or 4 Ollin	East
18	1 Tecpatl (Flint or Knife)	Chalchiuhtotolin	North
19	1 Quiyahuitl (Rain)	Tonatiuh	West
20	1 Xōchitl (Flower)	Xochiquetzal and Tezcatlipoca	South