The Yeniseian languages are a small family of languages which were spoken along the Yenisei River in Siberia. Only one of the languages is still living, which is Ket, spoken by about 20 people at the northernmost point of the Yeniseian languages’ historic range.
It’s thought that the Yeniseian languages’ urheimat was not actually particularly close to the range it had in recent centuries; instead, the language family is thought to have originated south of Lake Baikal, in Mongolia.
There is a proposal that the Yeniseian languages are related to the Na-Dené languages languages of North America. It seems like on the whole, linguists regard this connection as more likely than not, but it’s not yet settled science. However, there is also DNA evidence to support this theory: a genetic marker that is very common among Yeniseian people and uncommon among other north Asian people is practically universal among Amerindian people. (See also: settlement of the Americas)
Despite the language family’s current smallness, the Yeniseian languages were once quite influential on their neighbours. For example, the Turkic and Mongolic languages are thought to have borrowed titles like khan, khagan and tarqan, as well as the word for “god” and “sky” tengri, from Yeniseian. The extinct Indo-European language Tocharian also seems to have borrowed its vowel system from Yeniseian.