《将苑·卷二·北狄》
北方地区的游猎民族，没有固定的处所，哪里水草丰富，他们就到哪里去居住，遇至有利的形势，他们就南下入侵中原，反之，如果他们没有充足的力量就逃避到更远的北方。他们凭借险要的阴山和广阔的沙漠，有较强的自卫能力。饿的时候，他们就捕食野兽，寒冷的时候，他们就用兽皮作成衣被，每日奔走射猎，以捕杀动物为每天必做的事情，这样的民族，既不能被道德感化，也不会因战争所臣服。
北狄居无城郭，随逐水草，势利则南侵，势失则北遁，长山广碛，足以自卫，饥则捕兽饮乳，寒则寝皮服裘，奔走射猎，以杀为务，未可以道德怀之，未可以兵戎服之。
The nomadic tribes in the northern regions do not have a fixed place to live. They live wherever there is plenty of water and grass. When the situation is favorable, they invade the Central Plains in the south. On the contrary, if they do not have enough strength, they flee to the farther north. They rely on the险要 of Yinshan Mountain and the vast desert, and have a strong ability of self-defense. When they are hungry, they hunt wild animals. When they are cold, they use animal skins to make clothes and bedding. Every day, they run and hunt, and hunting animals is a must-do thing every day. Such a nation can neither be influenced by morality nor subjugated by war.