they were surrounded by darkness and dense gloom

In European historiography, the term Dark Ages or Dark Age refers to the Early Middle Ages, the period encompassing (roughly) 476 AD to 1000 AD.

This concept of a dark age was created by the Italian scholar Petrarch (Francesco Petrarca) in the 1330s, and was originally intended as a sweeping criticism of the character of Late Latin literature. Later historians expanded the term to refer to the transitional period between Classical Roman Antiquity 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 (for example, as shown in the impoverishment of a number of technologies, eg. in pottery). 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.

- Dark Ages en Wikipedia.

¿Qué pasó entre la caida del imperio romano y el principio de la era medieval? ¿Qué pasó entre el final de mis clases de joyería y este día? Dark Ages, man. Dark Ages.