The correct term to use for the worldwide period is “Middle Ages,” or the adjective medieval. The term “Dark Ages” has largely been retired in scholarly circles or narrowed to focus on the religious oppression in Europe. Now, I’m actually in the minority on this issue. I think the adjective “dark” was well deserved worldwide, Not just in Europe.
Historically, the term Dark Ages was used to describe the period between the 5th and 14th centuries, a religiously draconian time marked by economic, cultural, and scientific stagnation. The primary historical marker was a shift to organized religions worldwide.
I am not advocating for the return of the label “Dark Ages,” as I believe labels naturally evolve. This is particularly important when labels carry negative connotations. My argument for adding the adjective “dark” stems from the idea that the worldwide spread of organized religion caused a regression in human thought. Many well-known facts were lost.
Today, when scholars use the term “Dark Ages,” they are usually referring to a period within medieval Europe between 500 CE to 1500 CE. In western Europe, the Church became the dominant gatekeeper of education and acceptable knowledge. Illiteracy was used to control the public. Teach inside the approved framework and you might preserve approved texts. Teach against the approved framework and you could be branded a heretic. At times, that meant prison, torture, or death. That is the darkness I mean: not stupidity, but enforced de-education—the narrowing of public thought under religious power.
Although one force rarely explains a thousand years of history, just as the printing press later changed the world by expanding access to knowledge, organized religion changed the world by controlling the flow of knowledge.