It is called Dark Ages because of lack of written word. Beside few major events (in part of Europe) we have no idea what was happening in Europe for 500 years after fall of Roman Empire.
I would disagree with that;
There are a lot of Written Documents from the 500 years after the fall of the Roman Empire (West/476AD);
Mostly of course
Edicts & Codes of Laws of the Germanic successor Kingdoms; that however reveal a good insight into Governance, Society structure and Every Day life;
Also several Chronicles like those from Einhard, Paul the Deacon, Bede, Gregory of Tours etc.
And the Carolingian Renaissance is also very note worthy;
The reason i consider the
Dark Ages to be dark is because the Church
(but also the Guilds) had the monopoly on the knowledge and therefor the majority was literally kept in the dark;
This mostly changed with the improvement of Printing Press (
Moveable Letters/Gutenberg) when the knowledge
(and even Bibles for first time) were than possible to be distributed in quantity;
Notable example is the
Letter of Columbus of his voyage and discovery that spread rapidly across all of Europe;
Roger Bacon, Albertus Magnus or Thomas of Aquin were all Medieval scholars and most of the old Greek Knowledge
(+Islamic Persian/Arabic) was also already translated to Latin by the 12th and 13th centuries; Also the Arabic numerals were introduced to Europe (
Liber Abaci) in the early 13th cen. - the knowledge and understanding was already all there but only able to distribute sufficiently with the newer standards of the Printing Press (early 15th cen.) which ultimately
than (in my opinion) ushered in the Renaissance;