Aim: Forest relicts in the mountainous regions of Africa represent one of the most diverse ecosystems on our planet, but the processes that have generated this remarkable diversity are still poorly understood. We estimate divergence times for an endemic, flightless grasshopper family and reconstruct a potential scenario for their colonization of Africa to test the hypothesis that the diversity of these mountain-top endemics has been generated by multiple fragmentations and reconnections of tropical rain forests in parallel with climatic fluctuations. Location: Sub-Saharan Africa. Taxon: Lentulidae (Orthoptera) Methods: We inferred the phylogeny of 7 genera and 28 species of the Lentulidae based on COI, 16S and Histone 3 sequences by using a Bayesian approach, and we also estimated divergence dates. Based on our molecular phylogeny as well as the available information on the relationship of 6 additional genera and local occurrence records for 120 lentulid species across Africa, we reconstruct a potential colonization scenario for most species of this group. Results: Our findings indicate that the forest-bound lentulids of East Africa represent a monophyletic group that originates from South Africa. We show that major splits in the phylogeny of the Lentulidae coincide with three known fragmentation events of the African rain forests (27, 16 and 9 million years ago) and that lentulids subsequently diversified rapidly in parallel with the aridification and strong geological activity in East Africa. Main conclusions: Our results corroborate the diversification patterns reported for several endemic African forest-bound animal taxa at small scales and endemic African plant taxa at larger scales, highlighting the finding that much of the biodiversity presently found in the forest relicts of the Eastern Arc Mountains biodiversity hotspot has been generated by the interplay between humid periods that allowed the spread of forest-bound lineages across Africa and periods of aridity-driven isolation of forests and their associated fauna.