[blam]

"It is interesting to notice that a similar peak is also present at about half the 6th century, a time when, according to several Byzanthin historians quoted by Gibbon [5], e. g. Malala, Procopius and Theophanes, many scaring comets appeared in the sky. That was also the time of the great Justinian plague, which decimated the population of the Mediterranean region, killing up to 90% of the population according to some estimates. This depopulation was certainly a major factor which facilitated the Arab expansion some three generations later. "

The Dark Ages: Were They Darker Than We Imagined?

[umgud]

Have you read "Worlds in Collision" by Imanuel Velikosvky (sp?)?

[WestVirginiaRebel]

What about the "Mini-Ice Age" which occured in the Late Middle Ages? Could something like this have cause what we would now call nuclear winter effect?

[ASA Vet]

which decimated the population of the Mediterranean region, killing up to 90% of the population according to some estimates

10% or 90% is a rather large difference.

[Thud]

Check out Catastrophe: A Quest for the Origins of the Modern World by David Keys, about a titanic volcanic eruption in the Java-Sumatra area about 535 A.D. He has much to say on this subject.