From hydronymic and genetic data, it is suggested that the Yeniseian languages were spoken in a much greater area in ancient times, including parts of northern China and Mongolia.

[5] The Jie, who ruled the Later Zhao state of northern China, are likewise believed to have spoken a Pumpokolic language based on linguistic and ethnogeographic data.

Other groups—the Baikot, Yarin (Buklin), Yastin, Ashkyshtym (Bachat Teleuts), and Koibalkyshtym—are identifiable as Yeniseic speaking from tsarist fur-tax records compiled during the 17th century, but nothing remains of their languages except a few proper names.

Kott and Assan, another pair of closely related languages, occupied the area south of Krasnoyarsk, and east to the Kan River.

As an example, the toponym ši can be found in Zabaykalsky Krai, which is probably related to the Proto-Yeniseian word *sēs 'river' and likely derives from an undocumented Yeniseian language.

[19] The Yeniseians have also been hypothesised to be representative of a back-migration from Beringia to central Siberia, and the Dené–Yeniseians a result of a radiation of populations out of the Bering land bridge.

[20] The spread of ancient Yeniseian languages may be associated with an ancestry component from the Baikal area (Cisbaikal_LNBA), maximized among hunter-gatherers of the local Glazkovo culture.

[4] On the other hand, Václav Blažek (2019) argues that based on hydronomic evidence, Yeneisian languages were originally spoken on the northern slopes of the Tianshan and Pamir Mountains before dispersing downstream via the Irtysh River.

This was noted by Russian explorers during the conquest of Siberia: the Ket are recorded to have been expanding northwards along the Yenisei, from the river Yeloguy to the Kureyka, from the 17th century onward.

[23][24] Alexander Vovin argues that at least parts of the Xiongnu, possibly its core or ruling class, spoke a Yeniseian language.

[5] It has been further suggested that the Yeniseian-speaking Xiongnu elite underwent a language shift to Oghur Turkic while migrating westward, eventually becoming the Huns.

Despite these similarities, Yeniseian appears to stand out among the languages of Siberia in several typological respects, such as the presence of tone, the prefixing verb inflection, and highly complex morphophonology.

The following table exemplifies the basic Yeniseian numerals as well as the various attempts at reconstructing the proto-forms:[8][15][28][9] The following table exemplifies a few basic vocabulary items as well as the various attempts at reconstructing the proto-forms:[8][15][28][9] Until 2008, few linguists had accepted connections between Yeniseian and any other language family, though distant connections have been proposed with most of the ergative languages of Eurasia.

[29] At the time of publication (2010), Vajda's proposals had been favorably reviewed by several specialists of Na-Dené and Yeniseian languages—although at times with caution—including Michael Krauss, Jeff Leer, James Kari, and Heinrich Werner, as well as a number of other respected linguists, such as Bernard Comrie, Johanna Nichols, Victor Golla, Michael Fortescue, Eric Hamp, and Bill Poser (Kari and Potter 2010:12).

[30] One significant exception is the critical review of the volume of collected papers by Lyle Campbell[31] and a response by Vajda[32] published in late 2011 that clearly indicate the proposal is not completely settled at the present time.

[34] In 2001, George van Driem postulated that the Burusho people were part of the migration out of Central Asia, that resulted in the Indo-European conquest of the Indus Valley.

[42] The Sino-Caucasian hypothesis of Sergei Starostin posits that the Yeniseian languages form a clade with Sino-Tibetan, which he called Sino-Yeniseian.

[49] A 2023 analysis by David Bradley using the standard techniques of comparative linguistics supports a distant genetic link between the Sino-Tibetan, Na-Dené, and Yeniseian language families.

Bradley argues that any similarities Sino-Tibetan shares with other language families of the East Asia area such as Hmong-Mien, Altaic (which is actually a sprachbund), Austroasiatic, Kra-Dai, Austronesian came through contact; but as there has been no recent contact between Sino-Tibetan, Na-Dené, and Yeniseian language families then any similarities these groups share must be residual.

[50] Bouda, in various publications in the 1930s through the 1950s, described a linguistic network that (besides Yeniseian and Sino-Tibetan) also included Caucasian, and Burushaski, some forms of which have gone by the name of Sino-Caucasian.