The Bolivian Chaco on the margins of Pilcomayo River was a contested area during the 1800s. Tobas and other Indigenous Peoples boldly resisted the state’s occupation of their territories, keeping the frontier unstable for decades. I argue that Bolivian settlers gradually occupied the pastures along the river using violence, encouraged by state policies, and supported by army officers stationed in forts. Local merchants, Franciscan missionaries, and Avá-Guaraní neófitos played important roles in this process. I sought to better understand the viewpoints of state administrators and settlers. The views of Toba people remained opaque, beyond their actions to protect their lands from the ranchers’ encroachment. My approach combined ethnographic and historical methods to shed light on the expansion of the cattle-ranching economy from a perspective inspired in settler colonial studies.