The paper deals with the region bounded by the rivers Livenza and Isonzo, the Alps and the Adriatic sea. According to the great environmental diversity, the natural resources available in the Middle Ages differed within the area. Surface water was plentiful in the mountain area but it soaked into the ground in the high plain and resurfaced in the lowlands near the sea, which made river navigation and rafting of timber difficult. In the Middle Ages there were extensive forests in the mountains, in the hills and especially in the lowlands. The timber was commercially exploited and ended up mostly in Venice. Despite the poor mine production, intensive metalworking developed in the foothill villages where timber, raw materials, and hydraulic energy abounded.
