Yetis are an ancient species of ape-like animals that live in the hidden Valley of the Yetis.
They are very aggressive and feared creatures that will attack anything that provokes them with extremely powerful attacks and can endure any heavy weapon. Ajay first encounters a yeti after escaping Durgesh Prison, but passes out before the creature gets closer. Ajay is sent north to find something called "The Relic", which turns out to be yellow glowing tree that emits a yellow gas or yellow spores. Inhalation of the Relic's gas turns people mad: they begin to hear voices and see visions, and eventually are said to transform people into Yetis. A religious cult called the Disciples processed the product of the Relic into a liquid called "the Elixir" which they force feed to people so they become Yetis, which the Disciples revere. The Golden Path have only heard rumors that the Relic could be a powerful weapon that Yuma Lau sought and planned to use it against Pagan Min. The Golden Path sent Ajay and his pilot Sukhwinder to the Valley of the Yetis in order to retrieve it but their helicopter is shot down by the Disciples and crashes on a ridge of the hidden valley. Ajay wakes up from the wreckage to find his pilot is missing and starts hearing radio chatter from the Disciples cult about how they've kidnapped Sukhwinder and have isolated the valley. Eventually, Ajay came to see that the Lost Valley's caves are filled with luminescent fungi with ape-like statues, which the Disciples claim are depictions of Yalung. After attempting to rescue his pilot, Ajay is knocked out and first encounters the Yetis eating human flesh. Later on, Ajay finds the Yetis are being worshiped and feared by the Disciples who they call "The Awakened". Ajay encounters the Yetis the more he explores the valley, and they prove to be more powerful than any animal he's ever fought.
Standing taller than a man, the Yetis have greyish fur with a strange orange scaring on their chests and parts of their faces. Those found in the final mission of the DLC have white fur.
Yetis are very resilient to any firearm, including heavy weapons. When enraged they charge on all fours proving to be incredibly fast and knock over vehicles. The best way to kill one is to aim for their heads which will disorient them, then go behind them to perform a takedown which will kill them instantly.
A recommended weapon is the AMR which will kill them with a single shot and does not require Ajay to perform a takedown. The AMR is a signature weapon (A Signature Version of a Z93 sniper rifle) that can also be found within the Valley of the Yetis.
Although Yetis have high resistance towards most weapons, they can simply be run over and die on impact.
According to the expedition journals, some witnessed the Yetis drinking water from the hot springs which contain the orange substance from the glowing fungi, after analyzing the strange substance, men from the camp site began drinking the liquid and began feeling high and more powerful which made them more and more addicted to it. Side effects included screaming, hallucination, extreme aggression and inflammation around the faces and orange eyes. As a result, the men hid away in caves and began to mutate, which the Disciples call "Awakening". Finally over an unknown period of time they evolved into Yetis.
Much earlier in Kyrat's history, the road to the valley was cut off and destroyed because the Fungi was believed by the people to be a dark gift from the demonic entity known as Yalung. Out of fear they destroyed the pass allowing the yetis to fade into myth and legend. It seems that judging by the bodies those who drink the elixir undergo a mutated transformation within a dark environment, also there's a chance the chosen possibly die during the mutation process. Those who survive the process evolve into yetis but are put into a primitive state of mind relying entirely on instinct to hunt and kill anyone in their path.
According to notes of some Sandesh soldiers in the valley, to turn a person into Yeti without drinking anything you need to collect elixir and distill it, so an odor makes people start to suffer hallucinations and become Yetis, even if it is much more time consuming as with Digvijay, a civilian that was rescued by Ajay. Digvijay has hallucinations and voices in his head, similar to the changes, but only slower. Possibly, the Disciples made this process to delay the transformation because their skin is orange and the ultimate goal of those who follow Sandesh is to turn into an Awakened, which would occur in due time.