The A Region on the Move report series for the East and Horn of Africa has been the regional flagship publication since 2017. The series provides an advanced understanding of the main migrant groups and the environment in which mobility takes place, with a focus on internal displacement and mixed migration flows along the major migration corridors of this region. Building on the leading IOM World Migration Report series, the structure of the 2021 edition was revamped to explore mobility dynamics affecting the East and Horn of Africa region across its broader spectrum: from providing a regional overview of data and trends on international migrants to discussing specific groups of migrants, namely migrant workers, refugees, asylum-seekers, internally displaced persons and irregular migrants along the main migratory corridors. The revamped editions build on more than 20 data sources — official and operational — that examine different aspects of the multifaceted migration landscape.