Draft animals have been used for transportation for almost a millennium after the Neolithic Revolution enabled livestock farming and the development of wheel technology in the Metal Age. The main draft animals used are equids like horses, donkeys, and mules as well as bovines like oxen. Other animals commonly used for transportation include camelids as pack animals in Asia and South America, reindeer pulling sleds, and dogs in icy areas. Elephants have also been used for transportation in South Asia.