In his second book on cannabis, geographer Chris S. Duvall seeks to unearth the plant’s ‘African roots’ in world history, arguing that historians of cannabis thus far have neglected the important role of Africa and Africans in the drug’s story of global diffusion. This exclusion, Duvall writes, ‘comes from an intellectual tradition that marginalizes African contributions to world culture’, and, in the case of cannabis, ‘the act of smoking the herb and the technology of water pipes’ indigenous to Africa for nearly two millennia (p. 229).Divided into 3 parts and 10 chapters, The African Roots of Cannabis guides readers through the long history of psychoactive cannabis use in sub-Saharan Africa, from the plant’s arrival in East Africa from Madagascar sometime during the first centuries of the Common Era through its attachment to pre-existing indigenous smoking cultures in the Zambezi River valley to the subsequent diffusion of cannabis smoking throughout the continent and later the Atlantic world via the movements of exploited African labouring classes. The real contribution of Duvall’s study comes from his use of ‘language geography’, or the study of how languages spread, interact and transform both with and within geographic space, to trace the spread of cannabis smoking cultures, and particularly the use of water pipes (i.e. bongs), from Southeast Asia through Africa to the rest of the world. Drugs history orthodoxy avers that the culture of smoking originated with tobacco consumption among indigenous societies in the Western Hemisphere which was then expropriated and disseminated to the wider world via Europeans and their colonial trade networks after 1500. Duvall contends that this narrative is at best incomplete. In charting the spread of Bantu terms like ‘kachimbo’, meaning ‘water pipe’ and ‘mariamba’, meaning psychoactive cannabis and for the author the true origin of the term ‘marijuana’, from Africa to the Americas in Portuguese sources published during the fifteenth and sixteenth centuries, Duvall makes a strong case for the idea that ‘African knowledge underlies practices of psychoactive cannabis use around the Atlantic’, and particularly knowledge and practices of cannabis smoking (p. 131).