In the solar calendar of the Aztecs (Mexica), the xiuhpohualli, the year was divided into eighteen twenty-day months (veintenas) plus five unlucky days. Two consecutive months, the ninth and tenth, were devoted to honouring the dead. The ninth, usually called Tlaxochimaco ("the offering of flowers"), was also known as Miccailhuitontli, the Little Feast of the Dead; the tenth, Xocotl Huetzi ("the fruit falls"), was also called Hueymiccailhuitl, the Great Feast of the Dead.
Together they fell, in the sixteenth-century correlation, roughly in the late summer, around August and into September. Our knowledge of them comes above all from the great Franciscan ethnographic project of Bernardino de Sahagun, whose Florentine Codex set down in Nahuatl and Spanish the ceremonies of each month, and from the Dominican Diego Duran, though the two friars and their informants do not always agree on names and meanings.