This article seeks to move beyond simple narratives of decline and disappearance in the history of Brazil’s indigenous peoples during the nineteenth century. To do so, it examines the very sources that perpetuated the idea that Indians were vanishing: the writings of amateur ethnographers, in this case three authors who visited the Guaikurú and their descendants, the Kadiwéu, in western Brazil during the mid- to late nineteenth century. At first glance, these authors depict the remnants of a native society on its way to extinction. When analyzed in the context of colonial-era records and later ethnographies, however, they reveal important continuities in native strategies and modes of interaction with outsiders. In particular, the early ethnographies contain evidence of deeply rooted but flexible practices of alliance, appropriation, and resistance. Like many indigenous groups in the interior spaces of Brazil, the Kadiwéu used these strategies to defend their autonomy and territory during a century of challenges.