In this book J.B. Bury gives a detailed historical review of the Migration Period, also known as Barbarian invasions in Mediterranean countries. It describes widespread process of migrations of the Germanic tribes and the Huns within or into the Europe during the decline of the Roman Empire.

John Bagnell Bury (1861 – 1927) was an Irish historian, classical scholar, Medieval Roman historian and philologist. He objected to the label "Byzantinist" explicitly in the preface to the 1889 edition of his Later Roman Empire. He held the position of Erasmus Smith's Professor of Modern History at Trinity College Dublin.