Trecena

The original page 13 of the Codex Borbonicus, showing the 13th trecena of the Aztec sacred calendar. This 13th trecena was under the auspices of the goddess Tlazolteotl, who is shown on the upper left wearing a flayed skin, giving birth to Cinteotl. The 13 day-signs of this trecena, starting with 1 Earthquake, 2 Flint/Knife, 3 Rain, etc., are shown on the bottom row and the column along the right side.

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.

n.º	Trecena	Aztec deities associated	Cardinal point
1	1 Cipactli (Caiman or aquatic monster)	Tonacatecuhtli	East
2	1 Ehecatl (Wind)	Quetzalcoatl	North
3	1 Calli (House)	Tepeyollotl, Quetzalcoatl	West
4	1 Cuetzpallin (Lizard)	Huehuecoyotl or Macuilxochitl	South
5	1 Coatl (Snake)	Chalchiuhtlicue and Tlazolteotl	East
6	1 Miquiztli (Death)	Tonatiuh and Tecuciztecatl	North
7	1 Mazatl (Deer)	Tlaloc and Chicomecoatl o 4 Ehécatl	West
8	1 Tochtli (Rabbit)	Mayahuel and Xochipilli or Cinteotl	South
9	1 Atl (Water)	Tlahuizcalpantecuhtli or Xiuhtecuhtli	East
10	1 Itzcuintli (Dog)	Mictlantecuhtli	North
11	1 Ozomatli (Monkey)	Patecatl and Cuauhtliocelotl	West
12	1 Malinalli (Grass)	Itztlacoliuhqui	South
13	1 Acatl (Reed)	Tezcatlipoca or Uactli and Ixcuina or Tlazolteotl	East
14	1 Ocelotl (Ocelot or Jaguar)	Tlazolteotl	North
15	1 Cuauhtlil (Eagle)	Xipe Totec and Quetzalcoatl	West
16	1 Cozcacuauhtli (Vulture)	Itzpapalotl	South
17	1 Ollin (Movement or Earthquake)	Xolotl and Tlalchitonatiuh or 4 Ollin	East
18	1 Tecpatl (Flint or Knife)	Chalchiuhtototl	North
19	1 Quiahuit (Rain)	Tonatiuh	West
20	1 Xochitl (Flower)	Xochiquetzal and Tezcatlipoca	South

See also

• Aztec calendar
• Maya calendar
• Tonalpohualli
• K'atun