This series maps the activity of little-known military brigades and armed groups proliferating throughout the conflict in Yemen. Mapping these actors has become relevant for understanding future trajectories of violence in Yemen as some of them have developed significant combat capabilities with shifting allegiances. While some follow their own interests, others have clear allegiances to the internationally recognized government or the Southern Transitional Council. As with actors in other conflict scenarios, such allegiances are, however, never set in stone. Rather, allegiances are a fluid process, shifting due to changes of outside circumstances (e.g. the behavior of a patron) or battlefield victories. In order to be better prepared for these changes, this series maps the activity of such military brigades and armed groups — some of them have become relevant already, while others may see their turn towards increased relevance in the future.