So why did these people go to so much trouble to turn the entire mountains into terraces? Firstly, there are few large, flat areas of land in the region.Building the terraces therefore meant (3)that they could increase the areas in which they could grow rice.Secondly, (4)although the region has plenty of rain, the mountains are steep and the soil is shallow.The flat terraces catch the rainwater and prevent the soil from being washed away.