From what I understand on this issue is that no one really knows. The Huns did not have a written language so most of what we know comes from outside sources who tended to dislike the Huns and not take too much interest in their history. Most sources I have come across only state that they came from the East but that is as specific as they get. They did come further East than the Crimean area as they pushed the Goths out of this general area as they moved Westward and I am not overly aware of any population on the steppe between there and the Pacific that was horse-based that wasn't Turkish or Mongolian in origin. That being said, this was before these definition became solidified in any way as these groups tend to share many features in their culture and religion. Based on the fact that they were renouned for their horsemanship they were likely Turko-Mongolic people who have a long history of horsemanship and horse-based warfare.

Another question, I was taught in school that Atilla was Turkish (or at leasr Turkic), is their any truth to this?