Short answers, pulled from the story.
The Sayan Mountains stretch across southern Siberia, spanning from the Shapshal Range of the Eastern Altai in the west to the Abakan Range of the Kuznetsk Alatau in the east. This mountain range is situated between Russia and northern Mongolia.
The Sayan Mountains serve as the source for major rivers that flow across Siberia including the Yenisei River which travels over 3,400 kilometres to reach the Arctic Ocean. Tributaries merging here form the Yenisei River while other rivers flowing down from the Eastern Sayan ranges create deep gorges and waterfalls throughout the area.
During the Last Ice Age glaciers flowed down from the 3,492 m high Munku Sardyk massif situated west of Lake Baikal. Glaciers also covered summits between 2,600 and 3,110 meters in the Tunkinskaya Dolina valley before joining to create a parent glacier approximately 30 km wide.
Sayan reindeer herding represents the oldest form of reindeer domestication according to researcher Sev'yan I. Vainshtein. This practice is associated with the earliest domestication efforts by Samoyedic taiga populations living within the Sayan Mountains at the turn of the first millennium A.D.
The Soviet Union kept the Sayan Mountains closed as a protected and isolated area starting on the 1st of January 1944. This restriction remained in place until recent times limiting access to the region for decades while creating a unique environment where cultural influences developed separately from surrounding areas.