Pastoralism dictated the speed of land improvement. It required colonizing montane valleys conditioned by history to receiving ‘an immense deposit of labor.’ Shepherds and flocks at first followed ancient Roman Alpine transhumance routes, settling in low-elevation valleys. These valleys occupy one-fifth of all surface land of the district. Mountains reaching more than 1000 meters above mean sea level follow next, covering two-fifths of the landscape. They form the belt of Alpine forests that provided wood, limestone, and seasonal pastures. This vast warehouse of raw materials attracted more colonists in the early Middle Ages. Mountains of astonishing heights form the remaining northern fringe of the district, some exceeding 1500 meters above mean sea level. Here, heat, steep slopes, and sunlight turned unimproved grasses into good sources of high Summer pastures. Settlements surrounded the best available slopes, from the westernmost valleys of Sole and Non to the eastern valleys of Fiemme, Fassa, and Primiero. Each settlement had a unique shape and length, determined by the oppressive but generous hand of Alpine orography. All settlements shared the daring ambition of building a prosperous grazing and livestock economy.