Pretty much anything written by Peter Heather covers this time period. The Fall of the Roman Empire: a New History of Rome and the Barbarians Empires and Barbarians: Migration, Development and the Birth of Europe The Restoration of Rome : Barbarian Popes and Imperial Pretenders Goths and Romans 332-489 Rome Resurgent: War and Empire in the Age of Justinian (this book covers the 6th century and Justinian’s attempt to reconquer the west but it’s still excellent) I’m away from most of my books currently but I’m sure I have a list on my computer somewhere that I can look for and give you more suggestions