The period 1300-1600 saw an overlap between the processes of conquest and colonisation that took place in Europe during the Middle Ages and the transatlantic expansion of the Modern Age. As Latin Christendom launched the last crusades in the European continent, the Portuguese and Castilians established the first transoceanic colonies in the Eastern Atlantic, the African coast and in America. Many authors have contributed to the study of the connexions between medieval and early modern colonialism, and especially between the Castilian conquests in the Iberian Peninsula and in America. But most research has focused on the political, military, cultural and juridical aspects of the colonisation. In comparison, very few of them have concentrated primarily on the analysis of the agricultural practices and spaces that were used by indigenous peoples and settlers, which offers the possibility of learning how colonists altered the local landscapes and working processes to build a new agricultural system in the conquered regions. This PhD dissertation is a comparative study between two seigneurial towns that were colonised by Castile between the fourteenth and the sixteenth centuries and it aims to identify and juxtapose the strategies settlers implemented to manage the captured landscapes in two different environments: the seizure of Olvera (Cadiz) was part of the conquest of the Emirate of Granada, while the occupation of Agüimes (Gran Canaria) was one of the first steps of the European transatlantic expansion. This research has required dealing simultaneously with the written and the archaeological record, in combination with the analysis of modern landscapes and the carrying out of ethnographical surveys of the current managers of the working areas, and it has demonstrated that both case studies were part of a single process of conquest and dispossession of peasant communities which started in Frankish Europe during the Middle Ages. The study has evinced that colonists followed analogous strategies when managing the agricultural spaces captured to the local populations –which were eliminated- and adapting them to the colonial system of production. These transformations were primarily aimed at expanding farming areas, facilitating their control and the accumulation of agricultural output by rentier lords and large landowners and promoting the specialisation of fields in the monoculture of cash crops. The investigation has also shown a clear connexion between the rapid growth of the colonial working spaces and the spirals of accumulation by dispossession that followed the colonisation of both towns, which also accelerated the rate at which natural resources were consumed and rapidly deteriorated local ecological conditions. The comparison between the cases of Olvera and Agüimes has also revealed parallelisms between the way in which the indigenous peasantries organised agricultural production and built and managed their working spaces. Both the Andalusi and the Canarians imposed strict limits on the potential growth of farming areas and on the usage of natural resources, which were broken by the colonists to engage in uninterrupted sequences of field construction. It seems that this crucial contradiction between the constraints to growth established by indigenous population and the settlers’ tendency towards expansion and individual accumulation of resources seems lies at the heart of the systematic elimination of colonised societies by the Latin conquerors. The study of Olvera and Agüimes suggests that the elimination of the indigenous peasant organisations was a basic condition of the implementation and the reproduction of the colonising system in the conquered regions.