The sulung was both a unit of assessment for tax and other public obligations and a peasant landholding unit; it is found only in Kent. Like the corresponding units in other counties, the sulung was derived from the vocabulary of ploughing, sulh being the Old English word for a plough. The sulung was divided into four yokes, four of which composed the standard plough team. The sulung appears normally to have been twice the area of the customary hide or carucate, approximately 240 customary acres. Since customary acres were normally composed of scattered furlong strips whose size varied according to the nature of the soils and the shape of the fields, sulungs could vary in size from area to area, or even within the same manor.
Despite variations in size, however, individual sulungs could, like other peasant holdings, remain fixed in size over generations, even centuries, their integrity maintained by the power of the lord or the customs of the manor. They provided the stable base for both the manorial and the assessment systems.
For more detail, see Frederic Seebohm, The English village community (fourth edition, 1915); Alan Everitt, Continuity and colonisation: the evolution of Kentish settlement (1986); and Rosamond Faith, The English peasantry and the growth of lordship (1997).