Several folk stories about the yeti exist. The question that comes to our mind is why no one can find a yeti any more.

Local Sherpas believe that a ritual done hundreds of years ago wiped out the yeti population.

During the heyday of the Yeti several centuries ago, villagers in the Khumbu Valley were terrorized by the yetis. They killed yaks, stole crops and even attacked small children. Little children could not fall asleep at night and mothers were worried about whether their babies were going to be kidnapped.

The villagers went to the Lama who is a religious leader. The Lama mentioned that yetis had a weakness. They wanted to be like human beings. So they liked to copy our behavior. Also, they loved Chhang, which is the beer local villagers fermented.

In the past, the yetis raided the village and drank Chhang. So this is a weakness that the Sherpas could exploit.

The Lama told them to organize a party on a full moon night when the Yetis are watching. Meanwhile, he would perform a ritual that would bring bad omen to the dreaded creatures.

Based on the advice from the Lama, they put the chhang in large beer kegs and jars. The Sherpas started partying, dancing and pretended that they were drunk.

They also started a fighting game with swords and knives in hopes that the yetis would copy them later. They pretended to fight and kill each other. Some of the Sherpas faked death by laying on the ground.

After midnight, they left the Chhang, swords and the knives everywhere. Some villagers then went to bed while others observed from a distance if their plan would work.

The plan worked. The yetis flocked to the village after midnight and drank the Chhang. All of them got drunk. They also wanted to start a fighting competition with swords and knives. Soon they started fighting violently and killed each other.

In the end, only a couple of the Yetis survived. They fled to their caves but the damage was already done. The majority of the yeti population got wiped out during the drunken game.

Although the surviving yeti couple had children, the population never grew to the same level as before. The terror in the Khumbhu Valley ended and the villagers rejoiced. They would not be bothered and attacked by the yeti again.

Reference:
Yeti, The Abonimable Snowman, Fact or Fiction by Trilok Chandra Majupuria and Rohit Kumar (Majupuria), 1993.