The Horn of Africa has experienced, since decolonization, increased occurrences of various types of conflicts linked to bad governance, ethnic tensions, and environmental degradation, aggravated by the legacies of colonialism. Since the 1970s more specifically, Sudan and Somalia, two of the most unstable countries of the Horn, have witnessed major civil wars and instances of lower-level inter-communal conflicts between pastoralist groups who constitute a large portion of the population in both states. Inter-communal conflicts are largely fought between pastoralists and influenced by resource scarcity in semi-arid and arid regions. This paper analyzes the multiple and entangled sources of inter-communal conflicts in Sudan and Somalia from 1970 to 2000 to assess the relationship between environmental, political and social dynamics in a region of the world increasingly affected by environmental degradation and global warming, and evolving in a tensed political setting.