The Gulf and the Horn of Africa share a long history of economic and political engagement. In recent years, following a decade of political disengagement, the Gulf states have become once again major economic and political actors in the Horn region. Horn states have hardly remained passive clients, however, and actively court Gulf states for funding, as economic drivers and remittances have been a key factor for maintaining their domestic political settlements as well as a major determinant of conflict in the region. This report explores the extent and impact of Gulf state economic engagement in the Horn as well as the linkages between these financial streams and prospects for regional stability in the Horn of Africa. It traces the historic ties framing perceptions of the relationship between the regions, describes the determinants and instruments of Gulf investment, trade and aid to the Horn. It maps the scope of Gulf investments across Horn states and economic sectors, identifying approximately USD 13 billion between 2000 and 2017, mainly in Ethiopia and Sudan, across the agriculture, manufacturing and construction sectors.