Rituals celebrating the deaths of ancestors had been observed by these civilizations perhaps for as long as 2,500–3,000 years.The festival that developed into the modern Day of the Dead fell in the ninth month of the Aztec calendar, about the beginning of August, and was celebrated for an entire month.The festivities were dedicated to the goddess known as the "Lady of the Dead", corresponding to the modern La Calavera Catrina.
Originally, the Day of the Dead as such was not celebrated in northern Mexico, where it was unknown until the 20th century because its indigenous people had different traditions.
The people and the church rejected it as a day related to syncretizing pagan elements with Catholic Christianity.
Prior to Spanish colonization in the 16th century, the celebration took place at the beginning of summer.
Gradually, it was associated with October 31, November 1 and November 2 to coincide with the Western Christian triduum of Allhallowtide: All Saints' Eve, All Saints' Day, and All Souls' Day.
These flowers are thought to attract souls of the dead to the offerings.