To know the current land use, it is now usual to use satellite images, which offer higher and higher resolutions. To improve the knowledge, better distinguish the different types of plant formations or crops, we can use images, chosen according to phenology or cultural calendar. In any case, field surveys are needed: they allow to validate (or correct) the identified land use categories and to know the species in each ones. The task becomes more complex, when we want to identify landscape dynamics and thus know the past land uses. The oral communication will be based on PhD research conducted in Vietnam: the landscape dynamics were retraced to know the impacts of the Vietnam war on the landscapes at the provincial scale (Thua Thien Hue, central Vietnam). Going towards the past, the sources became more and more scarce. To know the land use at the end of the war, in 1975, only one image could be used, the only one available. It was one of the first satellite images and the resolutions were lower than now. For 1950’s, before the beginning of the war, satellite images were not yet available and we have to use aerial photographs. The oldest spatial data was a map, which was drawn in 1909 and gave a very cursory survey of plant formations. Except the map, these data were integrated and compared in a GIS to identify landscape dynamics between each date. But their reliability was lower than for the current state, as the land use categories could not be validated. Some archives were consulted but they gave limited information, which were hard to map. The solution was thus to conduct some interviews with inhabitants of the villages, where field surveys were carried out. They gave details about landscape dynamics, main species and their changes, besides information about the factors of dynamics, with the advantage of being more or less sited in a given space. This research shows the interest of an interdisciplinary study, mixing geomatic (remote sensing and GIS), botany/ecology (vegetation surveys) and sociology (interviews), to improve the knowledge of past landscapes and their dynamics.