Indigenous settlements were usually located in ravines, which provided caves for habitation. After the Spanish conquest, settlers went to the windward sides where water was more abundant and the soil more fertile. Pirate incursions from the fifteenth through the eighteenth centuries required that the main villages be located inland. During the eighteenth Century, an economic crisis and the necessity of increasing agricultural lands led to the clearing of large areas of forest and to the dispersal of settlements. More agricultural land was needed to feed the local population and to provide products for export. In the cities, and especially in the ports, a powerful commercial class composed of the families of old settlers and European immigrants began to emerge. At the beginning of the twentieth century, the growing of bananas, tomatoes, and potatoes for export to Europe increased. More recently, since the 1960s, the Canarian economy has been orientated toward tourism, causing wholesale urbanization on much of the coastal land formerly used for agriculture. At the same time, the local population moved inland. Also, during the last twenty years a strong internal migratory movement has led to the depopulation of the peripheral islands and an overpopulation of Gran Canaria and Tenerife, mainly in the capitals where trade and industry are important.