Proto-Yeniseian or Proto-Yeniseic is the unattested reconstructed proto-language from which all Yeniseian languages are thought to descend from.
It is uncertain whether Proto-Yeniseian had a similar tone/pitch accent system as Ket.
[1] Many studies about Proto-Yeniseian phonology have been done; however, there are still many things unclear about Proto-Yeniseian.
[2] The probable location of the Yeniseian homeland is proposed on the basis of geographic names and genetic studies, which suggests a homeland in Southern Siberia.
[3] According to Vajda, Proto-Yeniseian had the following phonemes, expressed in IPA symbols.