Short answers, pulled from the story.
The Sayan Mountains are located in southern Siberia, spanning southeastern Russia and northern Mongolia. The Russian territories they cover include Buryatia, Irkutsk Oblast, Krasnoyarsk Krai, Tuva, and Khakassia.
Mount Munku-Sardyk, standing at 3,491 meters, is the highest point in the Eastern Sayan and in the entire Sayan mountain system. It is located in the subrange of the same name in the southeastern portion of the Eastern Sayan.
The Yenisei River originates from tributaries fed by the peaks and lakes southwest of Tuva in the Sayan Mountains. It flows north for more than 3,400 kilometers before emptying into the Arctic Ocean.
According to scholar Sev'yan I. Vainshtein, the Sayan Mountains region is the origin of the world's oldest form of reindeer herding, practiced by the Samoyedic taiga population at the turn of the first millennium. The ancestors of modern Evenki groups are believed to have participated in this earliest domestication of the reindeer.
The Soviet Union kept the Sayan Mountains area closed beginning in 1944, making it a protected and isolated region. It remained closed throughout the Soviet period.
Linguist Juha Janhunen and other scholars place the homeland of the Uralic language family in the Sayan Mountains region of South-Central Siberia. Turkologist Peter Benjamin Golden separately locates the Proto-Turkic homeland in the southern taiga-steppe zone of the Sayan-Altay region.