This article develops borderland regionalisation as an analytical lens for under standing regional conflict systems, borderland political economy, and cross-border armed-group survival. Rather than treating regional conflict systems and cross-border armed group dynamics: the sudan–south sudan–car–drc nexus as a descriptive case, the ma nuscript argues that conflict in the Sudan-South Sudan-CAR-DRC space is best understood as a regional conflict system in which armed actors survive by arbitraging borders, exploiting differentiated state capacities, and embedding violence in trade, migrati on, and sanctuary networks. Anchored in Regional conflict systems theory (Buzan & Wæver; Lemke; Pugh & Cooper); small arms trafficking networks (Stohl; Florquin); political economy of border regions (Roitman). Theorises how conflict dynamics in one state a re constitutively linked to armed group behaviour, arms flows, and political alignments across a regional complex. the paper translates the topic brief into three linked questions: How do armed groups in the Sudan–South Sudan–CAR–DRC regional complex susta in themselves through cross-border resource extraction, arms acquisition, and safe haven access and what does this reveal about the regional political economy of armed conflict? What role do state actors particularly Sudan, Uganda, and the CAR governme nt play in managing, enabling, or suppressing cross-border armed group activity for strategic purposes? Under what conditions do regional conflict management mechanisms IGAD, ICGLR, AU effectively address cross-border conflict dynamics versus becomin g sites of competing state interests? Methodologically, it is organised around Regional political economy mapping using UN Panel of Experts reports, conflict event data (ACLED), and arms