《新唐书·列传·卷一百四十》
秦汉时以锐师猛将攻取黄河以南之地设立郡县，是不想让他们靠近中国。
且秦、汉以锐师猛将击取河南地为郡县者，以不欲使近中国也。
During the Qin and Han dynasties, we set up commanderies and counties by conquering areas south of the Yellow River using our sharp soldiers and fierce generals, because we did not want them to get close to China.