In Chile and Argentina, indigenous Mapuche intellectuals contend that there is a single Mapuche nation that spans the Chile–Argentina border. When Mapuche people talk about the Mapuche nation and create symbols to represent it, however, they can mean both the Mapuche nation within the Chilean and Argentine state borders and the cross-border Mapuche nation. The dual nature of this project raises important theoretical questions about the nation-building process. In this article, I argue that Mapuche activists are engaging in a multi-scalar geopolitical imagination. They are imagining the geographic, political and cultural elements of the Mapuche nation at two scales simultaneously: within nation-state borders and across them. The overlapping and contested nature of this process means that the nation-building project is full of new tensions and constraints. However, it is also an example of ‘thinking otherwise’ and imagining an alternative sense of national belonging.