One of the best books I read in 2021 was The Long Walk: The True Story Of A Trek To Freedom by Slavomir Rawicz. Published 1956 “The harrowing true tale of seven escaped Soviet prisoners who desperately marched out of Siberia through China, the Gobi Desert, Tibet, and over the Himalayas to British India.”
There is a bit in it that sounds like a yeti spotting to me.
I read the book because of the Ed Harris movie “The Way Back” 2010