 They change soil every year, and mark some off to spare, for they seek not a strenuous job in reaping from this fertile and vast land even greater yields—such as by planting apple orchards, or by fencing off fields; or by watering gardens; grain is the only thing they insist that the ground will provide.Tacitus discusses the shifting cultivation.The Migration Period in Europe after the Roman Empire and immediately before the Viking Age suggests that it was still more profitable for the peoples of Central Europe to move on to new forests after the best parcels were exhausted than to wait for the new forest to grow up.Therefore, the peoples of the temperate zone in Europe slash and burners, remained for as long as the forests permitted.