A packhorse or pack horse refers generally to an equid such as a horse, mule, donkey or pony used for carrying goods on their backs, usually carried in sidebags or panniers. Typically packhorses are used to cross difficult terrain, where the absence of roads prevents the use of wheeled vehicles. Use of packhorses dates from the neolithic period to the present day. Today, westernized nations primarily use packhorses for recreational pursuits, but they are still an important part of everyday transportation of goods throughout much of the third world.