A Region on the Move report series for the East and Horn of Africa has been the regional flagship publication since 2017. Over the years, the report series have illustrated the main humanitarian situations, 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. A Region on the Move 2021, the ninth report in the series, builds on more than 20 data sources — official and operational — that examine different aspects of the multifaceted migration landscape.