The Twitter-Demon used to push conversations my way where people had some kind of misapprehension ...
Anyway, Doomsdays, I know a tiny bit about the Greek "Dark Ages" and of the "Sea People" era before it.
I've also read about the European pre-medievval "Dark Ages", and a particulsr book on the subject by a famous scholar which/whose name(s) I cannot recall but had some very good bits about Islamic countries being in a "golden age" at the same time.