Reconquest
The confluence of borders, between the Kingdom of León and County of Castile, located in this area the battles between the two kingdoms. In 1037, Castile became the separate Kingdom of Castile. Alfonso X the Wise, in 1258 determined the ultimate limits with Valladolid, leaving Medina for the mountains of Torozos.
During the Middle Ages, in the Merindad of Valladolid Infantazgo (in old Castilian cited as: the Infantadgo of Ualladolid Meryndat), there was an administrative division of the Kingdom of Castile, which is described in the book Calif of Behetrías of Castile, drafted by the Cortes of Valladolid of 1351, when the establishment of the knights applied to King Pedro I for the absorption of the Behetrías land by conversion to manor.
Read more about this topic: Medina De Rioseco