The Day of the Dead or Día de Muertos is an ever-evolving holiday that traces its earliest roots to the Aztec people in what is now central Mexico. The Aztecs used skulls to honor the dead a millennium before the Day of the Dead celebrations emerged. Skulls, like the ones once placed on Aztec temples, remain a key symbol in a tradition that has continued for more than six centuries in the annual celebration to honor and commune with those who have passed on.

Once the Spanish conquered the Aztec empire in the 16th century, the Catholic Church moved Indigenous celebrations and rituals honoring the dead throughout the year to the Catholic dates commemorating All Saints Day and All Souls Day on November 1 and 2. In what became known as Día de Muertos on November 2, the Latin American Indigenous traditions and symbols to honor the dead fused with non-official Catholic practices and notions of an afterlife. The same happened on November 1 to honor children who had died.

Source: history.com for the complete article