Aztec calendar

After Reed, the cycle of numbers would restart (though the twenty day signs had not yet been exhausted), resulting in 1.

The set of day signs used in central Mexico is identical to that used by Mixtecs, and to a lesser degree similar to those of other Mesoamerican calendars.

Wind and Rain are represented by images of their associated gods, Ehēcatl and Tlāloc respectively.

The original Nahuatl term was "in cencalli tonalli" (a family of days), according to Book IV of the Florentine Codex.

In addition, each of the twenty trecenas in the 260-day cycle had its own tutelary deity: In ancient times the year was composed of eighteen months, and thus it was observed by the native people.

Bernardino de Sahagún's date precedes the observations of Diego Durán by several decades and is before recent to the surrender.

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 ancient Mexicans counted their years by means of four signs combined with thirteen numbers, thus obtaining periods of 52 years,[3] which are commonly known as Xiuhmolpilli, a popular but incorrect generic name; the most correct Nahuatl word for this cycle is Xiuhnelpilli.

A widely accepted version was proposed by Professor Rafael Tena of the Instituto Nacional de Antropología e Historia,[5] based on the studies of Sahagún and Alfonso Caso of the National Autonomous University of Mexico.

A correlation by independent researcher Ruben Ochoa interprets pre-Columbian codices, to reconstruct the calendar, while ignoring most primary colonial sources that contradict this idea, using a method that proposes to connect the year count to the vernal equinox and placing the first day of the year on the first day after the equinox.

[7] In this regard, José Genaro Emiliano Medina Ramos, a senior native nahua philosopher from San Lucas Atzala in the state of Puebla, proposes a multidisciplinary calendar reconstruction in náhuatl (‘centro de Puebla’ variant) according with his own nahua cosmosvision;[8] and relying precisely on Ochoa's smart correlation and on Tena's presuppositions as well.