The Boundaries of Ancient Trade is a new book that examines the political economy of the Afar Salt Trade in northern Ethiopia. The Afar is a valuable but logistically challenging region that once held economic interests for the ancient polity of Aksum (400 BCE–900 CE). The Danakil depression in the Afar is well-known for its salt pans where caravans of pack animals regularly travel to bring freshly mined salt back to commercial hubs at edge of the northern Ethiopian highlands. Helina Woldekiros’s new manuscript detailing ethnoarchaeological and excavation research along the salt trade is therefore a much-awaited contribution to our understanding of ancient Aksum’s long-distance economy.

After a short introduction, the book’s second chapter outlines the theoretical framework and research goals. Woldekiros’s key moves are to highlight potential heterarchical processes of the Afar trade and create methods for their investigation. Woldekiros reviews the Africa-focused heterarchy literature and finds currency in Guyer’s “niche economy”. Guyer’s distinctive version of niche economy emphasizes people’s ability to move between multiple economic niches and prioritize adaptation and resilience. “Niche” can refer to an economic interaction sphere historically found at the margins of dominant economies, a special area of production (and demand) that generates such economies, a role people occupy in these economies, or their entrepreneurial agency in creating such roles (Guyer, 1997, 2004). It is, in short, an economic space people make for themselves. Woldekiros’s focus on niche economy thoughtfully emphasizes how trade links diverse groups around the medium of salt. Commercial salt production requires a large labor force organized between mining, transportation, storage, and distribution that each entails their own support sub-industries. The patchiness of salt resources and the difficulty of procurement often lend salt trade to become a caravan-based trade. Woldekiros also points out that salt is a trade good valued both by commoners and elites, making it particularly suited for interrogating heterarchical/hierarchical social processes.

Chapter 3 reviews a political history of the Aksumite polity (400 BCE–900 CE). Woldekiros argues rightly that a long historical focus on elite power has masked non-elite participants in the Aksumite political economy. Woldekiros also brings forward Southall’s concept of the segmentary state in describing the Aksumite political sphere. Up until recently, heterarchy at Aksum had been alluded to by multiple researchers but never overtly studied. The one exception is perhaps an early entry by Kobishchanov (1981), primarily using foreign texts, which could be read as also converging on a segmentary state concept with Woldekiros. Woldekiros notes that Aksumite settlement patterns appear strongly influenced by trade along various local/regional interaction spheres, suggesting their importance to Aksumite political formations. Woldekiros argues that Aksumite trade (including the Afar Salt Trade) was state-centered but that non-state agents also participated on their own terms. Woldekiros connects the state to religious institutions such as churches found along the Afar trade routes.

Chapter 4 introduces the cultural geography of the study region that grounds the ethnoarchaeology. Woldekiros begins with a longer timeline of Ethiopian history to explain the archaeological history of the Afar. The chapter then explains the diverse social structures from which the participants of the Afar trade draw, and reviews common markers of personhood in the northern Horn including language, religion, highland/lowland human economies, household and community social organization (and architectures), and agricultural and pastoralist lifeways. It also outlines the physical geography of the trade routes leading into the salt pans.

Chapter 5 presents the ethnoarchaeological research. Woldekiros employed participant observation and interviews with the aim of creating comparative models to test hypotheses about the ancient Aksumite salt trade. The physical route is 72 km, but caravans generally trek between 132 and 220 km in actual distance. The author formed their own donkey and camel team to follow salt caravanners for 6 months. Through this research, we get an understanding of the participants and economic organization of the salt trade. We also gain insights into the potential archaeological patterning of material culture. Foodways is one area where lifeways diverge on the trade: men are responsible for cooking on the routes, instead of women, and they rely especially on breads, particularly the round birkuta found only along these trade routes. Cooking areas distinctive to caravans are therefore the most recognizable material correlate with a primary example being round sandstone cobbles used in birkuta-making hearths of a certain size. Meat sources are absent, being logistically difficult to transport. Woldekiros also makes notes on potential site formation patterns and differentiates between the location priorities of short-term and long-term camps. The chapter primarily delivers the conclusions of the ethnoarchaeological research, and I sometimes desired thicker descriptions of exchanges underpinning the conclusions. The portrait of this economy is a joy to read, however, and this is a data-valuable chapter for northern Ethiopian archaeology that I recommend for most audiences.

Chapter 6 reviews test excavations conducted at multiple sites near the modern towns of Agula and Desi’a. Agula is a salt trading center and medieval tax collection point located in the highland regions. Desi’a instead is located in a less agriculturally productive transitional zone. Desi’a is an excellent geographic example of town where people would need to engage in multiple economic niches rather than specializing in any one occupation. At each location, Woldekiros excavated test trenches at both a settlement site and a potential caravan campsite and also received permission to excavate at the church in Agula (Cherkos Agula). Many of the sites are multi-component, primarily dating to the Late Aksumite (~ 600–900 CE) or medieval/later historical periods (~ 1100–1700 CE) though classic Aksumite materials were also recovered. Most interesting are the caravan camp sites where the ethnoarchaeological hypotheses are put to the test. The primarily material correlates are again the birkuta-baking stones, the relative paucity of faunal bones at caravan sites compared to permanent settlements, and dung with embedded plant material indicating the presence of pack animals. Ceramics across the sites are diverse, suggested participation of actors from a range of backgrounds. Lithics are primarily informal tools made from obsidian likely originating in the Afar. A very few number of cowry shells (n = 4) may hint at linkages to the Red Sea trade. Notably, the depositions across sites tend to show an uptick in material culture for phases corresponding to Aksumite periods, suggesting higher activity during the time of the ancient polity. There must remain a caveat that these excavations represent a testing phase and are necessarily smaller sample sizes, but the arguments here are convincing. These archaeological data are interpreted in the last section for how they connect back to Aksumite history. A summarizing concluding chapter and end material close the book.

I think a dedicated discussion chapter could have aided wider readership. While interpretations of the material culture are present throughout Chapter 6, these may be missed by newer audiences not accustomed to reading archaeological data without some additional reinforcement. A few more visual materials and appendices, such as those summarizing radiocarbon dates and site phasing, would have also supported key messages. However, these are only details for the ease of data readability and the book more than easily accomplishes its research goals with exciting results.

While interplays of heterarchy and hierarchy are common themes in African archaeology, there is always a question of how we identify their varying material correlates by cultural region and history. I think hierarchy in particular appears difficult to find in Afar. For Woldekiros, the evidence of hierarchy is rooted in churches found near Afar trade routes, which are argued to index state actors based on post fourteenth century CE, tax collection records mentioning salt. This is extrapolated into the Aksumite period primarily based on the excavated redware pottery, which is in use about ~ 100 BCE–600 CE. The Aksumite king adopted Christianity about two centuries before the general population, so the church may represent a state actor if dating from the fourth to sixth centuries CE. However, merchant communities of the Red Sea also already valued Christianity as an identity marker long before this, and conversion may not have been so exclusively top-down across the entire northern Horn. I think connecting churches to state actors is possible—I especially like that it may explain the longtime observation of early churches evoking the design of Aksumite elite structures—but it introduces a number of attendant hypotheses. However, when considering the existing literature, arguing that churches were instead heterarchical would have perhaps been a bigger stretch. And when painting out what hierarchy may have physically looked like beyond abstract terms, I think this picture of state actors inevitably results, so the interpretations are fair reads and add to the accessibility of the book. It must also be noted that even if churches did not represent state actors, then this would only strengthen Woldekiros’s central argument on the heterarchical dynamics of the salt trade.

For recommended readership of this book: It is essential for anyone working in Aksumite archaeology or archaeology of the northern Horn extending into the periods after. Audiences will immediately see its value as a regional archaeology of the Afar, but it should also be regarded as a critical theorization of political economic dynamics behind complexity in the Aksumite period, of which there are few available. I also recommend this book for students and young researchers in Aksumite archaeology as an example of strong research design and hypothesis testing. Some audiences may benefit in pairing the manuscript with Woldekiros’s (2019) preliminary article that also iterates key themes. While the book is academic, it is still especially recommended for heritage professionals. The book seems to recognize and address this larger than average public-professional heritage audience in Aksumite archaeology and could be easily used for heritage advocacy. More general Africanist archaeology audiences may be interested for methods in uncovering caravan traces or salt trading in the past, or as a strong case study showcasing Guyer’s concepts.

I would also emphasize a contribution that may not be fully appreciated beyond regional specialists. Woldekiros states one of their reasons in engaging such extensive ethnoarchaeological research was to capture “history-in-the-making.” The Afar Salt Trade is one of the most active caravan trades in the world, where 70,000 pack animals carrying 10–20,000 tons of salt will trek between 132 and 220 km over a ~ 2000 m elevation change to Lake Asale, through volcanic landscapes famous for their active fumaroles, sulfur formations, pools of discharged acidic brine, and occasionally solidified frozen lava depending upon the eruptions of any given season or year, all through extreme temperatures that regularly exceed 50 °C in the daytime, and—as we see from Woldekiros’s research—create novel and divergent social forms as they travel these territories. The human element is often missing or marginalized in public literature on the Afar, and we see here concepts like niche economy working instead to showcase people’s agencies. Woldekiros’s illustrations then support a case for the Afar Salt Trade as a piece of living tradition in Ethiopia. This manuscript then provides us with a great window into this history-in-the-making.