All I can figure out is they left without women and acquired the greater part of their genetic background by purchasing/stealing brides ~ this is much like what the ancient Greeks and Trojans seem to have thought women useful for ~ slavery and trade goods (just in case anybody says "it's just not probable for the Huns to have captured brides".
Of course it's "probable".
In doing whatever it was they were doing the Huns even lost their original Chinese language and picked up a creole of vaguely Indo-European and Uralic-Altaic origin.
Because the Huns did this within the scope of history we are able to ascertain how "culture" can be transmitted from generation to generation without respect to the nations of origin, or the race of the participants.
Churchill is the guy who is responsible for calling the Germans "Huns" ~ he did it as an insult.
The Germans thought it quite inspirational.
We'll Get to the bottom of this using DNA
Nuclear and Mitochondrial Analysis of ancient Mongolian sample
"A majority (89%) of the Xiongnu sequences can be classified as belonging to an Asian haplogroup (A, B4b, C, D4, D5 or D5a, or F1b), and nearly 11% belong to European haplogroups (U2, U5a1a, and J1). This finding indicates that the contacts between European and Asian populations were anterior to the Xiongnu culture, and it confirms results reported for two samples from an early 3rd century B.C. Scytho-Siberian population (Clisson et al. 2002)."
Read this:
On The Presence Of Non-Chinese At Anyang
Pretty Blond Headed Mongoloid Girl
Like the Maori.