Abstract: Recent international relations (IR) scholarship has developed a growing awareness of this discipline’s colonial roots, prompting a search for decolonising approaches. This article is about indigenous sovereignties and how they have been occluded in the currently globalised European system of states. The method employed is a case study of two of the most impoverished and brutalised Indigenous Peoples in Brazil: the Guarani and the Kaiowa. In an attempt to transit between the world of Westphalia and non-European worlds, it starts by engaging in a conversation with Guarani and Kaiowa knowledge. Then, through a long-term historical analysis, it examines the main colonial processes that caused the occlusion of Guarani and Kaiowa sovereignty. Finally, it provides a broader perspective on how the diffusion of the European model of sovereignty, confronted with Indigenous resistance, has led to the social exclusion of Indigenous Peoples worldwide.