The work is based on little-known, fascinating primary sources: four beautiful manuscript maps of the Pacific Lowlands of the viceroyalty of the New Kingdom of Granada that are housed in the Archivo General de la Nación (Bogotá, Colombia) and The Library of Congress (Washington, DC). These maps were traced and colored at different times in the second half of the eighteenth century, and their precise reproductions are part of the book’s appendix. The first four chapters critically explain why these maps have such historically revealing information, as well as their difference from printed maps of the period.

As the author states, this differentiation can be explained by local and imperial perceptions of political viewpoints. Similarly, she notes that, for the Pacific Lowlands, manuscript maps document the less idealized facets of the past. The precision of details that illustrate concrete historical situations or point out seemingly insignificant details, such as the course of a river, the boundary of two parcels of land, or the influx of canoes at a river mouth, are a kind of data that allow us to interpret social, economic, political, and environmental facts that, at first glance, seem not to be intertwined. This is the principal strength of the book.

These kinds of micro-scale features—which are the opposite of graphic ornaments—constitute the informative strength of the handwritten maps that were developed in the field by baquiano [local expert] cartographers, who, in addition to their own experiences, made daily use of valuable empirical information provided by Indigenous, Black, mulatto, and zambo individuals—that accumulation of men and women, “people of all colors,” who lived in riverside settlements scattered in the lowland jurisdictions. In this regard, Wiersema makes an important comparative point: Despite their scientific conventions that included measurements and distances and their grandiloquent cartouches and showy colors, European maps (i.e., those of the French or Dutch) do not usually graphically indicate the historical and social accuracies that their Spanish manuscript counterparts illustrate about the localities and inhabitants of the Pacific Lowlands. River navigators, Cuna Indians, enslaved people, fishermen, manatieros, miners, and peasant smallholders are the subjects who exercise agency through this book, which explains the socioeconomic realities expressed in the manuscript maps. In contrast, rivers such as the Atrato, Yurumanguí, Naya, and Dagua are the fluvial axes used to analyze the historical singularities of this fragment of the South American tropics in the times of the unfinished and often inoperative Bourbon reforms. The author’s focus on these specific rivers is another major strength.

Wiersema affirms that Chocó was much more than a border periphery for centers of political power and merchant capital, such as Santa Fe or Popayán. In fact, according to its high but incalculable gold production, the Pacific Lowlands were essential for the functioning of the viceregal economy, both formally and informally—a fact that is perceptible in the information on the maps. For this reason, it is suggested that, in some maps drawn by state initiatives, such as the one ordered by Viceroy Francisco Antonio Moreno y Escandón (1772), details were intentionally omitted to safeguard information of monarchical interest, especially about gold resources. The gold extracted from the mines located in the rivers of the Chocó continued to arouse considerable interest among the European enemies of the Spanish empire during the eighteenth century.

Although this work contains specific excessively descriptive passages that distract from the main lines of narrative and argument, the methodology is innovative. The primary sources from historical archives in Colombia and Spain are rigorous and well organized. In her analytical counterpoints, she dialogues with most Colombian historians investigating the Pacific Lowlands during viceregal times. In addition, the work highlights the agency and political tensions of subaltern subjects such as Indigenous and enslaved people in the face of monarchical powers, and it does not lose sight of comparisons with other frontier regions in the overseas domains of the Spanish empire. The book is recommended for upper-level and graduate seminars.