In the early stages of settling human tribes tended to till the land in a group. Caesar, in Gallic War ([52 BC] 1996) describes how amongst the ancient Germans "there were no separate estates or private boundaries." Tacitus ([98 AD] 1999) elaborates that the Germans practiced the so-called "shifting cultivation" -- making a plantation, reaping the crop and then moving on. This kind of land usage does not need fences but in the long run it leads to wide-range destruction of woods and severe soil erosion so it is usually called "predatory cultivation" or "land-mining" (Liversage, 1945.)