External involvement in the Horn of Africa dates back hundreds of years, as major powers and regionally influential state and non-state actors have found the sub-region strategically important. As a result, they have entered into periodic power rivalries while seeking to influence the political, economic and social development of the local states and societies. However, although external involvement over recent decades has encouraged economic development, the competition between foreign powers for influence and local actors’ exploitation of such rivalries have favoured the persistence of endemic political instability in the Horn of Africa.