Traditionally and for a long time, duvets were mostly flat rectangular shaped things, which was what they were originally. They acted as padding, keeping a person warm and also protecting the person from the cold during the night. When duvets started to be used, even historically, they came from animals, such as horses. There were a number of reasons for people using horses or other animals for their duvets. The first and obvious reason was that horses were a known resource which was easy to trade. People used their duvets and beds to trade with. However, some people used the horse skin for protection from the cold and also used the hair for insulation. This is one of the reasons why horse duvets did not last for very long. They also, if left for a long time, were difficult to clean and smelt.