<P> The land - holding tenants also had livestock, including sheep, pigs, cattle, horses, oxen, and poultry . Pork was the principal meat eaten; sheep were primarily raised for their wool, a cash crop . Only a few rich landholders had enough horses and oxen to make up a ploughing - team of six to eight oxen or horses, so sharing among neighbours was essential . </P> <P> Much of the land in the open - field system during medieval times had been cultivated for hundreds of years earlier on Roman estates or by farmers belonging to one of the ethnic groups of Europe . There are hints of a proto - open - field system going back to AD 98 among the Germanic tribes . Germanic and Anglo - Saxon invaders and settlers possibly brought the open - field system to France and England after the 5th century AD . The open - field system appears to have developed to maturity between AD 850 and 1150 in England, although documentation is scarce prior to the Domesday Book of 1086 . </P> <P> The open - field system was never practised in all regions and countries in Europe . It was most common in heavily populated and productive agricultural regions . In England, the south - east, notably parts of Essex and Kent, retained a pre-Roman system of farming in small, square, enclosed fields . In much of eastern and western England, fields were similarly either never open or were enclosed earlier . The primary area of open fields was in the lowland areas of England in a broad swathe from Yorkshire and Lincolnshire diagonally across England to the south, taking in parts of Norfolk and Suffolk, Cambridgeshire, large areas of the Midlands, and most of south central England . This area was the main grain - growing region (as opposed to pastoral farming) in medieval times . </P> <P> The population in Europe grew in the early centuries of the open - field system, doubling in Britain between 1086 and 1300, which required increased agricultural production and more intensive cultivation of farmland . The open - field system was generally not practised in marginal agricultural areas or in hilly and mountainous regions . Open fields were well suited to the dense clay soils common in northwestern Europe . Heavy ploughs were needed to cut through the soil and the ox or horse teams which pulled the ploughs were expensive, and thus both animals and ploughs were often shared by necessity among farm families . </P>

What do you mean by open fields and commons