wooden bar or frame used to join draft animals at the heads or necks so that they pull together. In the early Middle East and in Greece and Rome, oxen and onagers were yoked across the horns or necks. Control of a team of yoked beasts was difficult. Furthermore, ancient yokes pressed against a hard-pulling animal's windpipe, choking it. The invention of the horse collar solved this problem and led to the replacement of oxen by horses. In some areas of the world, however, oxen still are yoked together much as they were in medieval Europe.