> Yeniseian (the originator of such words as Tengri, Kha(g)an, etc) being connected to Native American Apache language was pretty amazing and evidence of the importance of paleo-linguistics in finding out informations about our ancestors

This is a bit controversial, though. I haven’t read through the original papers, but one person who did so informed me that they found this relationship not very convincing at all. Still, it’s fascinating stuff!