Originally posted by DarthMaur
Do you guys have any statistics on this?
I have no written statistics, but having studied part of the period I can vouch for the essential truth of the paucity of sources.
The period between c.600 and c.800 is just very sparse in Christendom for evidence. A few chronicles if you are lucky, but their evidence tends mostly the be highly localised. Most history of this time comes from writers some centuries later writing down what happened. Also, states at this time were not bureaucratic, and so less paper was produced. Alot of evidence in the middle ages, and in antiquity, is bureaucratic in nature. In the ninth century things start to pick up again, but evidence does not exceed the levels found in antiquite till around the 11th century - partly at least because from the 11th century the states of western Europe become more bureaucratic once more.
For Byzanium the situation is a little different, but the 7th century is very sparse, picking up again a little in the 8th, but only really recovering in the 9th.