This development took place in the Late Middle Ages (13th to 15th centuries) and Early Modern Period (16th to 18th century), because disease (e.g. The Plague) and famine led to a significant decline in population and the total number of settlements fell sharply (leaving abandoned villages), as a result of wars and economic circumstances. Thus, during the colonization of the mountains, areas were often cleared that, because of the nutrient-poor sandy soils, were unsuitable for farming and had to be abandoned after a short period because of overuse and overexploitation. Also, the use of the forest to obtain firewood and timber did not follow the principles of sustainability. On the one hand, the production of straw (foliage as bedding for cattle) and wood pasture damaged the soils and forests; on the other hand the manufacture of iron, glass and potash, which needed a lot of wood, led for centuries to the overuse and destruction of the forest and thus to the further impoverishment of the population. Occupations that the forest itself supported, such as lumberjacks, charcoal burners, rafters, resin burners (pitch boilers) and ash burners, supported only a meagre existence.