One of the most remarkable manifestations of social cohesion in large-scale entities is the belief in a shared, distinct and ancestral past. Human communities around the world take pride in their ancestral roots, commemorate their long history of shared experiences, and celebrate the distinctiveness of their historical trajectory. Why do humans put so much effort into celebrating a long-gone past? Integrating insights from evolutionary psychology, social psychology, evolutionary anthropology, political science, cultural history and political economy, we show that the cultural success of historical myths is driven by a specific adaptive challenge for humans: the need to recruit coalitional support to engage in large scale collective action and prevail in conflicts. By showcasing a long history of cooperation and shared experiences, these myths serve as super-stimuli, activating specific features of social cognition and drawing attention to cues of fitness interdependence. In this account, historical myths can spread within a population without requiring group-level selection, as long as individuals have a vested interest in their propagation and strong psychological motivations to create them. Finally, this framework explains, not only the design-features of historical myths, but also important patterns in their cross-cultural prevalence, inter-individual distribution, and particular content.