It is an ecosystem derived from human activity in the environment of the Mediterranean forest populated by holm oaks, cork oaks and a wide variety of shrub species. It is therefore the consequence of conquering land from the forest for pastures. It goes through an initial phase in which the tree density is clarified, to move to a second control of the woody vegetation and the stabilization of the grasslands.

The Extremaduran and Alentejo pasture is formed in a clear forest, where cereals are grown or the land is used to maintain cattle, sheep or bristles, together with the kinetic activity and the use of other forest products (wood, cork, mushrooms, etc.). In these unique lands, Iberian pork is raised in a mountaineering regime, feeding on the acorns of holm oaks and cork oaks.

The adehesado system has great economic and social importance in the Iberian Peninsula, both for its superficial extension and for the function of fixing the rural population in its original nuclei, as it reduces the migration flow and its consequences ( increase in mortality rates, reduced activity rates, cessation of farms, etc.).

The extension of the dehesa de Extremadura and the Alentejo occupies an important territory of the north, center and south of these demarcations. As for its importance in the Iberian peninsula as a whole, it varies greatly depending on the oipinon of the different authors. But between two and four million hectares are stretched between Spain and Portugal, mainly in the center, southwest and west. In Spain the territories of Extremadura, Andalusia (Seville, Córdoba, and Huelva), Salamanca, and in Portugal are highlighted by extensive areas of the Alentejo and Algarve.