Guard hair is the name for the outer layer of coarser, longer hairs of the mountain goat, the yak, some camelids and other mammals inhabiting extreme climates. The undercoat that does the real work in providing a soft, fine, dense coat right next to the skin, is the one that is highly prized for .warmth and softness.
As it is so incredibly strong and resilient the guard hair is used for weaving anything of substance and weight such as carpets, carpet bags, tent hangings etc.