The Migration Period, also known as the Barbarian Invasions (German: Völkerwanderung "migration of peoples"), was a period of intensified human migration in Europe from about 400 to 800 AD. This period marked the transition from Late Antiquity to the Early Middle Ages. Migrations were catalyzed by profound changes within the Roman Empire and on its "barbarian frontier". The migrants who came first were Germanic tribes such as the Goths, Vandals, Lombards, Suebi, Frisii and Franks; they were later pushed westwards by the Huns, Avars, Slavs, Bulgars and Alans. Later migrations (such as the Arab conquest and Viking, Magyar, Moorish, Turkic, and Mongol invasions) also had significant effects (especially in North Africa, the Iberian peninsula, Anatolia and Central and Eastern Europe); however, they are outside the scope of the Migration Period.

Germanic peoples moved out of southern Scandinavia, Denmark and adjacent lands between the Elbe and Oder rivers after 1000 BC. The first wave moved westward and southward (pushing the resident Celts west to the Rhine River by about 200 BC) and moving into southern Germany up to the Roman province of Gaul by 100 BC, where they were stopped by Gaius Marius and Julius Caesar. It is this western group who was described by the Roman historian Tacitus (56 – 117 AD) and Julius Caesar (100 - 44 BC). A later wave of German tribes migrated eastward and southward from Scandinavia between 600 and 300 BC to the opposite coast of the Baltic Sea, moving up the Vistula near the Carpathians. During Tacitus' era they included lesser-known tribes such as the Tencteri, Cherusci, Hermunduri and Chatti; however, a period of federation and intermarriage resulted in the familiar groups known as the Alamanni, Franks, Saxons, Frisians and Thuringians.