The historian Procopius, in his "History of the Wars", recorded that in the mid 530s something occurred which caused the sun to be covered by a dust veil, and that this continued for a year. Similar reports come from China, Japan, and Ireland. All across the world in the 530s, crops failed, famine struck, and then, in the 540s, in the Mediterranean, a strange disease began to spread among the populace. This was the Plague of Justinian--the first recorded instance of the Black Death which would return to ravage Eurasia in the 1300s. What we know about the Plague of Justinian, and the bizarre weather of the 530s, which apparently was caused by volcanic eruptions and caused a climatic downturn where temperatures decreased by at least three degrees worldwide, is changing rapidly. This video explains what we currently know of what, to many, seemed to be an apocalyptic time. And, as reflected in the primary sources, it is for this reason that historians have begun to discuss the 530s, with the Plague of Justinian, Justinian's wars of reconquest, his building program, financial panics, barbarian invasion, and the climate issues, as the true end of the Roman Empire.
SOURCES:
The Fate of Rome, Harper
New Approaches to the Plague of Justinian, Sarris
New Rome, Stephenson
Catastrophe, Keys
The Ruin of the Roman Empire, O'Donnell
Plague & the End of Antiquity, Little
Justinian's Flea, Rosen