Sahelian transhumance is a seasonal movement of herds based on strategies. These strategies are based on environmental and socio-economic factors. However, it is empirically difficult to establish the influence of each factor on the spatio-temporal distribution of herds. This paper presents a microsimulation software Sahelian transhumance simulator (STS). STS determines the spatio-temporal influence of each factor on herd movements. It also proposes scenarios for developing and securing the Sahelian pastoral space.