This article analyses the phenomenon of “boros” and urban violence in the peripheries of Cartagena, Colombia, during the post-peace agreements era. The concept of boro offers an alternative approach to understanding the dynamics and configuration of violence that emerge in the urban peripheries of Caribbean cities. It proposes an alternative perspective to the concept of the gang, typically used in American studies. The concept also offers an alternative explanation to violentology by focusing on boros as central actors in the configuration of urban criminality. Using southern theory as developed in sociology by Connell (Southern theory: The global dynamics of knowledge in social science. Polity Press, 2007), the chapter examines how boros are intertwined with illegal economies and local power structures, playing a key role in the territorial governance of marginalised areas. The study is based on 3 years of original ethnographic fieldwork, introducing concepts such as criminal capital and criminal habitus to understand how the dynamics of violence are learned and transmitted within these groups. The article critiques the dominant narrative that has minimised the impact of boros on urban violence and argues that, far from being a marginal phenomenon, boros are a fundamental component of the social and criminal reorganisation underway in Cartagena, Columbia.