 The early Middle Ages were a period of climatic deterioration , with a drop in temperature and an increase in rainfall , resulting in more land becoming unproductive . Climate change had a major impact on agriculture in this period and terms emerged to describe different quantities of land . In the period c . 1150 to 1300 , warm dry summers and less severe winters allowed cultivation at much greater heights above sea level and made land more productive . Arable farming grew significantly , but was still more common in low @-@ lying areas than in high @-@ lying areas such as the Highlands , Galloway and the Southern Uplands . The main unit of land measurement in Scotland was the ploughgate , also known as the davoch and in Lennox as the arachor . It may have measured about 104 acres ( 0 @.@ 42 km2 ) , divided into 4 raths . The average amount of land used by a husbandman in Scotland might have been around 26 acres . 
