Title kinda speaks for itself. The fact that most of our languages descend from a group of nomads that possibly were the first to domesticate horse seems like a big deal to me. Why hasn't this permeated to our education?
This is still a hotly debated topic in linguistics. I suggest reading about the Indo-European debate for some background info. There was been lots of research into this question, some less reputable than others (i.e. Gimbutus). Recent genetic research has has solidified the Trans-Caucasian steppes as the most likely birthplace for PIE (Proto-Indo-European language). Before the recent genetic publications, most regional claims on PIE were based on a combination of archaeology and historical linguistics. Historical linguists reverse engineers a language based on common morphological changes. While not an "exact science", languages generally evolve in specific patterns. Another major tool is historical lexicon, or vocabulary. For example a historical linguists would suggest the Trans-Caucasian Steppes because early lexicons include the word for wheel, which was first utilized in this area. While using archaeology at the primary tool in the dissemination of PIE, another scholar might suggest Anatolia because of the dispersal of farming practices across the Near East. It's all very complicated, and the nature of the evidence means that it's still contested. The advent of new genetic studies still hasn't necessarily confirmed much since genetic data just shows that movement of people and not necessarily culture or language itself.
Sources: The Horse, the Wheel and Language by David Anthony