Much of the post-Cold War discourse about contemporary warfare posits a binary opposition between a ‘democratic peace’ in the North and the prevalence of virulent ‘new wars’ in the South. This article seeks to qualify these accounts by bringing out the deeper historical and sociological legacies of state formation critical for understanding the emergence of an internal peace amongst developed countries and the continuing insecurity and multiple civil wars in many poorer developing regions. It is argued that two features of Southern state formation – the external imposition of states and the enforced norm against territorial aggrandisement – have significantly constrained the development of many developing states, making it more difficult for them to forge strong, synergistic states whose security concerns are externally- rather than internally-oriented. The article argues that there is, though, much variation in how Southern states have responded to these historical legacies of state formation. The article concludes with a four-fold taxonomy to replace the simple North-South bifurcation, differentiating between developed, globalising, praetorian and failed states and identifying the differing potential for, and incidence of, violent conflict, insecurity, and war within these four types of state.