Landlord-peasant land relationships embodied in different management strategies and forms of possession, constitute a central chapter in the medieval and modern agriculture history of the Castilian crown. In the following text, we analyse its evolution within the extended monastic patrimony of León, connecting it to social and economic circumstances between the end of XIIth century and the beginning of the XVIth century. Understanding them becomes all the more important since they play a key role in the explanation of exploitation field patterns applied in the modern era and of the agriculture system where they thrived.