Why are the Middle Ages sometimes called the Dark Ages?

I assume the middle ages are called the dark ages because that is when the great depression was or something im not sure

the answer is expolration. hope this !

depending on what kind of map for example a pltical maps works in many ways this iss how it works it shows the areas and places the democratics and the repbulcicans reside for example if   texas chooses trump for president there a republican state and if   califronia chooses hillary there a democratic state.