The Tumi is a sacrificial ceremonial axe, or knife as it is most commonly referred to, distinctly characterised by a semi-circular blade, made of either bronze, copper, gold-alloy, wood, or silver alloy and is often inlayed with semi-precious stones such as lapis lazuli. Tumis are most often associated with Pre-Inca cultures in the Peruvian Coastal Region and in a few cases with the Inca culture itself. The most common examples of the tumi are associated with the Peruvian cultures of the Chimor (also referred to as the Chimu, which represents the style of art from this culture), ad the Lambayeque (also known as the Sipan or Sican). In Andean mythology, the Moche, Chimu and Incas were descendants of the Sun God, Inti, who was worshipped annually with an extravagant celebration known as the Inti Raymi, which is still alluded to today in the form of the Inti Raymi Festival. The festival took place at the end of the potato and maize harvest in order to thank the Sun for the abundant crops or to ask for better crops throughout 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 a few body disturbance additional than that associated with injury, perhaps an organic or mental condition. The tumi knives used in the earlier cultures of Peru, such as the Paracas, were likely different in composition than those of the later Lambayeque and Chimu, as tumis from these cultures were only functional in a symbolic ceremonial manner, to do the use of soft metals. These soft metals wouldn't have allowed for the actual killing of animal or cutting of any kind of flesh.
Tumi knives were produced for ritual use by elite members of society which included them being used in elite burial ceremonies. On November 21, 2006, archaeologists announced that they had unearthed 22 graves in northern Peru containing pre-Inca artifacts. Among the artefacts were the first tumi knives ever discovered by archaeologists. All previous examples had been recovered from grave looters.
In 1936 a tumi was discovered in the valley of Batan Grande, Illimo, Lambayeque, Peru. It is really more an axe than a knife with a weight of 992 grams, height 41 cm. This tumi is believed to have the figure of Naylamp on its top, as a large number of tumis are thought to have a depiction of this symbolic figure. Naylamp was a mythic hero and founder of the Lambayeque, or Sican, culture, that was begotten from a totemic bird with his same name, Ñaylamp. The legend goes, that when Ñaylamp died, or disappeared, after founding the Lambayeque culture, he grew wings and flew into the sky. This hero-king founder of Lambayeque built a temple named Chot where he placed a large stone that he called Llampallec, which means statue of Ñaylamp. In this temple a large number of ceremonies and rituals were offered using a tumi. The knife or Tumi of Illimo is represented with a mask of a bird, wings and bird shaped eyes. The mythic storeys about the bird named Ñaylamp and the hero warrior founder of Lambayeque are represented in the knife or Tumi of Illimo by a birdman. Tumi knives often include depictions of birds or winds in order to symbolise Ñaylamp as well.
In modern Peru, to hang a tumi on a wall means good luck. The tumi is the national symbol of Peru and has become a symbol used in Peruvian tourism publicity and can be found depicted on tourist gifts such as mugs and key chains.