The mongolic tribes of the xiongnu empire was made up of the tribes Turkic, Tocharian, and Iranian ect.
Idk what document but It was just at the time, and even now, as it gave a strict yet fair in a sense punishment, lets say you stole something, they would chop off the hand you used to steal. It was a way to keep people from committing crimes and funny thing is it really worked.
