 Scotland is roughly half the size of England and Wales and has approximately the same amount of coastline , but only between a fifth and a sixth of the amount of the arable or good pastoral land , under 60 metres above sea level , and most of this is located in the south and east . This made marginal pastoral farming and fishing the key factors in the pre @-@ modern economy . Its north Atlantic position means that it has very heavy rainfall , which encouraged the spread of blanket peat bog , the acidity of which , combined with high level of wind and salt spray , made most of the western islands treeless . The existence of hills , mountains , quicksands and marshes made internal communication and conquest extremely difficult . 
