The Dark Ages
The somewhat iffy, not quite academic name for the period after the Roman empire took a header up till William the Barsteward decided he fancied engerland as a weekend holiday home. (450ad till 1066ad for those of you with a date fixation)
So called because humanity had its collective head up its arrse and was of the opinion that it had all gone dark.
Leading from the front during this period were the Vikings who kicked everyones back doors in. MEN (in a pointed, swordy way), WOMEN (in a bit of a stiffy kind of a way), CATTLE (in whatever way suited them best at the time) and MONKS (in a rob you blind sort of a way).
While the west was in a total arrse up, the east (Muslims and Byzantines) were busy inventing double entry book keeping, napalm, REALLY strong coffee, religious bigotry, the number 0, red tape and the first IED.