What language did the Xiongnu speak?

The Yeniseian people are interesting, my sources were mainly from Alexander Vovin. The Ket people have lived among the Uralic Selkups for long and they have both loaned and mixed with each other, though generally the Ket were more influenced by the Selkup than the opposite. it’s likely that the Yeniseians came from a back migration from America to Siberia.