In the 10th–13th centuries, agriculture expanded into the wilderness, in what has been termed the "great clearances". During the High Middle Ages, many forests and marshes were cleared and cultivated. At the same time, during the Ostsiedlung, Germans resettled east of the Elbe and Saale rivers, in regions previously only sparsely populated by Polabian Slavs. Crusaders expanded to the Crusader states, parts of the Iberian Peninsula were reconquered from the Moors, and the Normans colonized England and southern Italy. These movements and conquests are part of a larger pattern of population expansion and resettlement that occurred in Europe at this time.