Colombia’s peace process with the FARC-EP has brought a significant reduction in the national levels of violence. Yet, in certain regions of the country the demobilisation of Colombia’s former largest guerrilla has been accompanied by rising rates of violence. The municipality of Tumaco in the extreme south of the country’s Pacific coast is a case in point. In this paper, we demonstrate that a historical and socio-geographic perspective on the shifting dynamics of the armed conflict helps shed light on current developments in Tumaco. In particular, the analysis reveals a specific co-evolution of the FARC-EP presence and of the drug economy in the region, which helps explain key features of violence in the contemporary post-conflict context. The study provides important insights into Colombia’s current peace process as well as, generally speaking, into the complex territorial dynamics of crime and violence during transitions to peace.