The litter is a class of wheelless vehicles, a type of human-powered transport, for the transport of persons. Examples of litter vehicles include lectica (ancient Rome), jiao (China), sedan chairs (England), palanquin (also known as palki) (Bangladesh, India), gama (Korea), cáng (Vietnam) and tahtırevan (Turkey). Smaller litters may take the form of open chairs or beds carried by two or more men, some being enclosed for protection from the elements. Larger litters, for example those of the Chinese emperors, may resemble small rooms upon a platform borne upon the shoulders of a dozen or more men. To most efficiently carry a litter, porters will attempt to transfer the load to their shoulders, either by placing the carrying poles upon their shoulders, or the use of a yoke to transfer the load from the carrying poles to the shoulder.