Recent research on the Inka has documented the strategies and effects of imperial administration at a provincial and household level. Less is known, however, about the structure and dynamics of the Inka frontier and its impact on local and economic processes. The southeastern Inka frontier—according to ethnohistoric record—was the setting for conflict between the Inkas and the Guaraní-speaking Chiriguano groups from the Chaco piedmonts and Amazonian lowlands. In the context of two competing frontier models, one military (a hardened perimeter or in-depth defense) and one cultural (with wide socioeconomic processes), this article evaluates the nature of the southeastern Inka frontier and its effects on local socioeconomic dynamics. Archaeological and ethnohistorical research at Oroncota and Cuzcotuyo, two Inka centers of this frontier, suggest an alternative in the form of a “soft military frontier” formed by outposts and imperial centers disembedded from local socioeconomic processes. While architecture reveals high levels of investment, settlement data, storage capability, and the distribution of Inka imperial materials all suggest a minimal involvement in local socioeconomic processes. The results are relevant to understanding Inka frontier strategies and provide a case study of frontier interaction between a highly organized prehistoric state and tribal populations.