The Agricultural Revolution in Scotland was a series of changes in agricultural practice that began in the 17th century and continued in the 19th century. They began with the improvement of Scottish Lowlands farmland and the beginning of a transformation of Scottish agriculture from one of the least modernised systems to what was to become the most modern and productive system in Europe. The traditional system of agriculture in Scotland generally used the runrig system of management, which had possibly originated in the Late Middle Ages. The basic pre-improvement farming unit was the baile (in the Highlands) and the fermetoun (in the Lowlands). In each, a small number of families worked open-field arable and shared grazing. Whilst run rig varied in its detail from place to place, the common defining detail was the sharing out by lot on a regular (probably annual) basis of individual parts ("rigs") of the arable land so that families had intermixed plots in different parts of the field.[1]: 149 [2]: 24