Anette Idler summarizes some of the findings from her new book Borderland Battles, which reveals how violent non-state groups compete for territorial control, co-operate in illicit cross-border activities and replace the state in exerting governance functions in borderlands. Borderlands are like a magnifying glass on some of the most entrenched security challenges of the world. In unstable regions, border areas attract violent non-state groups ranging from rebels and paramilitaries to criminal organisations who exploit their neglect by central governments. These groups compete for territorial control, cooperate in illicit cross-border activities, and substitute for the governance functions usually associated with the state. Studying the Colombian borderlands where armed conflict and organised crime converge demonstrates that the gap between state-centric views on …