Confused?

Second post! Wow. Anyhoo.
So in grade school the Dark Ages was taught as a period of darkness where nothing particularly good happened (at least nothing that led to anything else).
In history of science last term, we were told that the Dark Ages were wrongly named and that they were a period of at least some prosperity and that grade school was wrong.
In music history we were taught that the Dark Ages weren't dark and were somewhat prosperous.
And in Foundations of American Ed, we were taught that the Dark Ages was a period of great stagnation in which nothing of any importance happened.
So which is it?!
Make up your minds!
It's confusing!
One period of time can't be overall both prosperous and stagnant. That's an oxymoron (just like how I found this powder at work called dumpster fresh...it's supposed to make dumpsters not smell bad, but that's impossible! They will always stink!).
And that's my mental conundrum for the day.
Have a happy night!