《魏书·列传·卷四十三》
汉代不设王畿，则以方比之数为郊郭的位置，所以东郊八里，南郊七里，西郊九里，北郊六里，中郊在西南未地，离都城五里。 
汉不设王畿，则以其方数为郊处，故东郊八里，南郊七里，西郊九里，北郊六里，中郊在西南未地，五里。 
No king's domain was set up in the Han Dynasty, so the number of the direction times eight was used as the location of the suburb. Therefore, the eastern suburb is eight li, the southern suburb is seven li, the western suburb is nine li, the northern suburb is six li, and the middle suburb is in the southwest unknown location, five li far away from the capital.