This paper studies the political and institutional responses recently given to population mobility between the Horn of Africa and the Arab world. It stems from a fieldwork conducted in the Yemen, in Sudan and in Saudi Arabia among public administrations, private sector institutions and migrant communities. It confronts the weberian definition of the modern state which implies territorial and population control with the “government” of mobility encountered in Sudan, in Yemen and in Saudi Arabia. Refugee movements, economic migration, transit and circular mobility challenge receiving and transit countries in their modern state ethos. Continuing population movement due to permanent political instability and economic crisis lead Arab states neighbouring the Horn of Africa to design political and administrative arrangements meant to manage population mobility. But various determinants and contexts account for the forms institutions take. 1) The political economy of institution building in Saudi Arabia reflects the ambiguity of labour import policies: demographic concerns and unemployment issues raise political problems for different political actors who have been trying, since the early 1990s, to bind market based logics and implement saudisation policies. 2) Regional diplomacy, domestic politics and international intervention influence the Sudanese management of a large refugee population. Refugee law and institutions, as well as ad hoc diplomatic responses to refugee arrivals and claims, reflect the political sensitivity of forced population movements at the margin of the Arab and African regional systems. 3) American and European influence on Yemeni politics since 9/11 accounts for the greater coercion of population movements, especially on refugee trends from the Horn of Africa. From these three case studies, we describe the evolution of state control on population movements in different contexts. In Sudan, the state negotiates its autonomy vis-à-vis international intervention on refugee issues in order to gain independence on conflicting domestic politics. In Saudi Arabia, it reasserts demographic concern over labour market preferences and international regulation and tries to nationalize its labour market. In Yemen, the government is making the most out of the country’s transit position on refugees and migrants’ routes and of the security agenda of foreign powers in the region. In a comparative perspective, this paper refers to the history of state institutions devoted to migration management and refugee issues, to the study of jurisdictional arrangements concerning refugees and migrants (refugee law, labour law, immigration law), to the sociology of institution building.