Therefore, its known narrative elements are not a part of the Doctor Who universe as we, on this Wiki, choose to define it. It may have been the basis for a similar story in another medium, however — and that story may indeed be valid.
The Yeti was a story concept in John Leekley's series bible for Amblin Entertainment's proposed 1990s Doctor Who television show. The story was based on the Second Doctor serial The Abominable Snowmen.
Still seeking his father, the Doctor visits the Dalai Lama in 1953 Tibet. The Lama tells the Doctor that the Yeti are feeling threatened by Edmund Hillary's expedition to the top of Mount Everest. There are gunshots and a battle, although no one gets more than a glimpse at the Yeti. The Doctor dissuades the team from hunting the Yeti in the morning. The group then meets with the Yeti, who are really the last Neanderthals, and Hillary agrees to protect them by maintaining the myth of their ferocity.