This article’s aim is to present an empirical study on the know-how behind the understanding of footprints and traces on sand. This study is based on pastoral nomadic and semi-nomadic populations living in Sahara and Sahel regions. More precisely, the conclusions exposed in this brief study are the results of, in the one hand, a PhD work realized with Tuaregs Kel Ewey, populations from Aïr region in the North of Niger, and in the other hand, exploratory investigations recently carried in the North of Chad with Tubus Daza and Bideyat populations and in the South of Niger with Tuaregs Kel Gress. Identify, interprete the associated signs, find the individual : these are skills coming from a pastoral know-how. The punctual examination of footprints is meant to identify the individual that produced it ; the search for signs associated to the traces allows to discover other elements revealing, more generally, the behavior of this moving individual in a spatial and temporal context ; while tracking of traces, using an hodological approach, allows to finally meet up with the individual. In addition, this study touches upon power games between the people that possess the know-how being understanding traces : they are the key to either a continuity or a subversion of the social order. Finally, this study explores the remaining and transforming aspects of this know-how in a world on the way to sedentarisation.