《淮南子·地形训》
北方幽暗不明，是天地闭合，寒冰积聚，动物蛰藏的地方。那里的人体形短缩，脖子短，肩膀宽而臀部下垂；身体的各个孔窍与阴部相通，骨骼的发育也与阴部功能相关；北方属黑色主管肾脏；那里的人愚笨但长寿。那里的土质适宜种豆类但马狗很多。
北方幽晦不明，天之所闭也，寒水之所积也，蛰虫之所伏也，其人翕形短颈，大肩下尻，窍通于阴，骨干属焉，黑色主肾，其人蠢愚，禽兽而寿；其地宜菽，多犬马。
The far north is dark and cloudy, a place where the heavens and the earth come together, cold ice accumulates, and animals go into hibernation. People there are short and stocky with short necks, broad shoulders and drooping buttocks. Their lower bodies' orifices are connected to their sexual organs, and their bone development is also related to sexual function. North corresponds to the color black and governs the kidneys. The people there are dull but long-lived. The soil is good for growing beans, but there are many horses, dogs, and wild animals.