Upvote:4
The Xiongnu, Hephtalites and Huns may have spoken Turkic languages. However, there are a lot of uncertainties about these groups of people (are they three different groups or only one? Did the Huns speak one language or several? etc etc) so that no-one knows for sure.
Also note that languages spoken in areas that are only suitable for nomadic pastoralism can change quite often (Mongolia is a good example for that, but one might argue the northern shore of the Black Sea is similar) while urban and farming areas tend to be more stable in that regard. Even today Samarkand and Bukhara (both in Uzbekistan) are supposed to be mostly Persian-speaking.