The Migration Period, also known as the Barbarian Invasions, was a period in European history marked by large-scale migrations that saw the fall of the Western Roman Empire and subsequent settlement of its former territories by various tribes, and the establishment of the post-Roman kingdoms.
The term refers to the important role played by the migration, invasion, and settlement of various tribes, notably the Franks, Goths, Alemanni, Alans, Huns, early Slavs, Pannonian Avars, Magyars, and Bulgars within or into the former Western Empire and Eastern Europe. The period is traditionally taken to have begun in AD 375 (possibly as early as 300) and ended in 568. Various factors contributed to this phenomenon of migration and invasion, and their role and significance are still widely discussed.
Historians differ as to the dates for the beginning and ending of the Migration Period. The beginning of the period is widely regarded as the invasion of Europe by the Huns from Asia in about 375 and the ending with the conquest of Italy by the Lombards in 568, but a more loosely set period is from as early as 300 to as late as 800. For example, in the 4th century a very large group of Goths was settled as foederati within the Roman Balkans, and the Franks were settled south of the Rhine in Roman Gaul. In 406 a particularly large and unexpected crossing of the Rhine was made by a group of Vandals, Alans and Suebi. As central power broke down in the Western Roman Empire, the military became more important but was dominated by men of barbarian origin.
There are contradictory opinions as to whether the fall of the Western Roman Empire was a result of an increase in migrations, or both the breakdown of central power and the increased importance of non-Romans resulted in internal Roman factors. Migrations, and the use of non-Romans in the military, were known in the periods before and after, and the Eastern Roman Empire adapted and continued to exist until the fall of Constantinople to the Ottomans in 1453.