haircloth -
Cloth made of the mane or tail hairs of a horse.
Wikipedia
Haircloth is a stiff, unsupple fabric typically made from horsehair and/or from the wooly hair of a camel. Although horsehair generally refers to the hair of a horse's mane or tail, haircloth itself is sometimes called horsehair. Horse or camel hair woven into haircloth may be fashioned into clothing or upholstery.
