From Wikipedia

The Dark Ages

The Dark Ages is a term referring to the perceived period of cultural and economic decline and disruption that took place in Western Europe following the decline of the Roman Empire. The label employs traditional light-versus-darkness imagery to contrast the "darkness" of the period with earlier and later periods of "light". Originally, the term characterized the bulk of the Middle Ages as a period of intellectual darkness between the extinguishing of the light of Rome, and the Renaissance or rebirth from the 14th century onwards. This definition is still found in popular usage, but increased recognition of the accomplishments of the Middle Ages since the 19th century has led to the label being restricted in application. Today it is frequently applied only to the earlier part of the era, the Early Middle Ages. However, modern scholars who study the era tend to avoid the term altogether for its negative connotations, finding it misleading and inaccurate for any part of the Middle Ages.

The concept of a Dark Age originated with the Italian scholar Petrarch (Francesco Petrarca) in the 1330s, and was originally intended as a sweeping criticism of the character of Late Latin literature. Petrarch regarded the centuries since the fall of Rome as "dark" compared to the light of classical antiquity. Later historians expanded the term to refer to the transitional period between Roman times and the High Middle Ages, including not only the lack of Latin literature, but also a lack of contemporary written history, general demographic decline, limited building activity and material cultural achievements in general. Popular culture has further expanded on the term as a vehicle to depict the Middle Ages as a time of backwardness, extending its pejorative use and expanding its scope.