In the Middle Ages, the area remained a zone of little interest. No written documents exist prior to the 12th century that mention the region. It is known, however, that between 711 and 740 AD the Berbers had stationed troops in the valley of the Duero, but the majority of these peoples left the area because of a severe drought that occurred sometime between 750 and 753 AD. Only the most important centers of habitation survived (Medina del Campo, Olmedo, Alcazarén, Tordesillas, etc.).