 Mule trains have been part of working portions of transportation links as recently as 2005 by the World Food Programme.A mule train is a connected or unconnected line of pack mules, usually carrying cargo.Because of the mule's ability to carry at least as much as a horse, their trait of being sure-footed along with their tolerance of poorer coarser foods and abilities to tolerate arid terrains, mule trains were common caravan organized means of animal powered bulk transport back into pre-classical times.