Mexica Calendar System

Timeline

1. c. 600–1325Valley of Mexico · Valley of MexicoThe 260-day sacred calendar cycled through 13 numbers and 20 day names, while the 365-day solar calendar comprised 18 months plus 5 unlucky days; before the Mexica arrived in the valley, this dual calendar system was already operating maturely in cultures such as Teotihuacan and the Toltecs.
2. 1381–1390Priestly quarter of Tenochtitlan · Valley of MexicoIn the 1380s, the priestly corps of Tenochtitlan scheduled annual festivals such as the New Fire ceremony, the war god's birthday, and the rain god festival according to the dual calendar; almanacs (amoxtli) recorded day names and divinations; the calendar cycle determined market days and agricultural rhythms, closely linked to rituals at the Great Temple.
3. 1390–1521Aztec Empire · MexicoFrom the 1390s to the early 16th century, the Mexica calendar spread and standardized across the empire; the New Fire ceremony (xiuhmolpilli) held every 52 years marked the end of the great calendar cycle, with all lights extinguished and new fire rekindled, symbolizing cosmic renewal and the continuation of the ruling order.