The Tumi is a sacrificial ceremonial knife distinctly characterized by a semi-circular blade, made of either bronze, copper, gold-alloy, wood, or silver alloy usually made of one piece and used by some Inca and pre-Inca cultures in the Peruvian Coastal Region. In Andean mythology, the Moche, Chimu and Incas were descendants of the Sun, which had to be worshiped annually with an extravagant celebration. The festival took place at the end of thepotato and maize harvest in order to thank the Sun for the abundant crops or to ask for better crops during the next season. During this important religious ceremony, the High Priest would sacrifice a completely black or white llama. Using a tumi, he would open the animal's chest and with his hands pull out its throbbing heart, lungs and viscera, so that observing those elements he could foretell the future. Later, the animal and its parts were completely incinerated.
Other Andean cultures such as the Paracas have used the tumi for the neurological procedure of skull trepanation. Many of these operations were carefully performed, suggesting that the surgery was done for the relief of some body disturbance other than that associated with injury, perhaps an organic or mental condition.
Tumi were produced for ritual use and for burials of elite members of society. On November 21, 2006, archaeologists announced that they had unearthed 22 graves in northern Peru containing pre-Inca artifacts. Among the artifacts were the first tumi ever discovered by archaeologists. All previous examples had been recovered from grave looters.