The business of map-making was the handmaiden of colonialism, as those sitting around the 1884–5 conference table in Berlin were acutely aware. While prospecting for areas of geo-political and economic interest, lines were drawn on a cartographical outline by a handful of European powers eager to stake their claims to the African continent. The process of filling in the unknown spaces of an empty map with topographical detail and place names was the next phase of colonization, along with the act of securing local treaties. Yet how borders within and across colonial zones were negotiated on the ground is a subject that has attracted little historical attention. This is why Camille Lefebvre's book is such a remarkable contribution.

Frontières de sable traces the shifts in local and colonial notions of spatial boundaries, and ensuing negotiations and contestations over border drawing in the Central Sudan (primarily Niger and northern Nigeria) before and during the colonial occupation. This study is not concerned with trans-border commercial exchange or the movement of people. Nor does it seek to document how colonialism shaped geographical realities. Rather, it is about the changing meanings of borders and boundaries in Saharan-Sahelian regions in the course of two defining centuries, with particular attention paid to the roles Africans played in colonial map-making as both ‘actors and targets’ (p. 13). Arguably, one of the book's chief insights is Lefebvre's insistence that the colonial domestication of the African landscape was always informed by indigenous knowledge, and at times even dictated by African political interests. Here she joins the work of others, such as Hélène Blais on Algerian cartography, who have examined the dialectical nature of colonial knowledge. Lefebvre argued that colonial map-making was a product not of blind foreign imposition, but of an interchange of contrasting epistemological cultures. Her book showcases a number of maps that were either drafted by African informants, or based solely on knowledge they provided. Lefebvre examines the dialogue between two composite approaches to geography. The first is a local African (Hausa, Kanuri, Tuareg, Zarma…) understanding of the border as a ‘mouth’ with spatial boundaries and political frontiers often fluid and mobile as dictated by temporal authorities. The second is a French linear relationship to space defined by connecting dots on paper to create fixed territorial units. Explicating the terms of this dialogue, with its deliberations, misunderstandings, and stakes, is the principle aim of Frontières de sable.

This book is based on extensive research, primarily undertaken in archives. Lefebvre's method is avowedly neither ethnographic, nor informed by oral sources. It is one of ‘archival immersion’, which is attentive to the voices and narratives embedded in written records. The book, divided into three parts, each containing three or four chapters, includes a collection of original documents and maps in appendices.

Part One examines varying conceptual imaginaries and knowledge registers about Saharan-Sahelian spaces and frontiers. Lefebvre launches, somewhat predictably, with a discussion of a dozen or so travelogues of European ‘explorers’ who crisscrossed the central Sahara Desert. She makes interesting remarks about the body of works as a whole, noting the average lengths of travel time, the fact that most travelers acquired local languages, and that they journeyed solo within well-established caravan circuits in which social and political conventions shaped the parameters and rules of travel. The next chapter examines the modalities of mobility and spatial orientation based on these and other sources. It speaks of a fluid Sahelian space where villages, such as those around Lake Chad and even large cities such as Gobir and Kano, were displaced as a result of environmental episodes.

The last chapter in this section draws on the jihad literature produced by the Dan Fodio scholarly family, to determine that Muslim scholars had a limited interest in geographical information. It includes a discussion about a map, which must have inspired the title of Lefebvre's book. It was reproduced from Edward Bovill's Mission to the Niger and originally collected by the British Captain Clapperton. The map first was drawn in the sand by Caliph Mohamed Bello and reproduced on paper by his learned men (mallamai). It situates the Sokoto Caliphate amidst a series of frontiers linked to a long-drawn history of territorial expansions and contractions. The author observes that in the nineteenth century, regional insecurity, linked to conflicts in the aftermath of the Sokoto jihad, caused East-West instability that disrupted North-South commercial exchanges, and would lead to significant shifts, such as the rise of Kano to the expense of Katsina as a central trans-Saharan trade terminus.

Parts Two (1880–1922) and Three (1922–64) focus on the logic and logistics of conquest, with a special focus on the French colonization of Niger – a colonial territory carved out of geopolitical interest as a means to unify France's African empire. This specific context explains why Niger was administered militarily and on a shoestring, with minimal investments in human or physical capital. When approaching the unknown, the French relied on hired informants and even ‘secret agents’ charged with collecting information about commercial and religious networks of circulation and itineraries. In 1890, British and French diplomats agreed on paper on the official border between their respective West African territories. But it would take ten years for either colonial power to take possession; the French in Niamey did not put in place a civil administration until 1922. After this time, the French reconfigured boundaries based on a revised logic bent on promoting ‘geographic and ethnic uniformity’ (p. 324) within territorial units.

Frontières de sable collapses the frontiers of French colonial history in insightful ways. The book is well written and filled with interesting anecdotes. At times the analysis seems somewhat synthetic, especially when it appears to lump together the geographic mindscapes of culturally diverse groups, accounting little for differences among sedentary and nomadic communities. This shortcoming is not entirely surprising when considering the author's dependency on textual sources. The drawing of colonial borders is a subject typically examined from the point of view of politics and diplomatic history. Lefebvre complicates our understanding of border making by demonstrating the extent to which African knowledge systems permeated colonial policy, even to the point of determining in certain times and places the actual placement of colonial frontiers. This is a bold reevaluation of the question of the artificial nature of colonial frontiers and a welcome introduction to an important debate.