This article seeks to explain both China's motivations in, and South Korea's response to, the Koguryo controversy. It argues that it is necessary to take into account the role of national identity and domestic politics in explaining the controversy. China's claim is neither defensive nor offensive toward the two Koreas; rather, it is a logical consequence of a particular historiography in China that was developed in the twentieth century. Given the centrality of national identity construction in both countries, the conflict over Koguryo will be difficult to resolve in the future. To prevent future conflicts from reoccurring, both sides need to adopt a new perspective on history to move toward a shared history and cultural community. © 2012 Taylor & Francis.