Okay, I know I'm an archaeologist, but surely I can indulge myself in a bit of history occasionally!
My big thing is the so-called Dark Ages of Britain, the period from the abandonment of Britain by the Roman government early in the fifth century to the consolidation of the kingdoms of England and Scotland in the ninth and tenth centuries. I object to the term ‘Dark Ages’, but it's difficult to think of a better phrase to sum up this difficult period. ‘Early medieval’ is the continental term but in Britain, we tend to use it to mean 1066-1200 (or thereabouts); ‘Sub-Roman’ effectively excludes the English, Picts and Scots, and only applies to the fifth and sixth centuries anyway; ‘Anglo-Saxon’ excludes the Welsh, Picts and Scots… I'm at a loss to find a decent term.
So, with that proviso, these links take you into my pages on the ‘Dark Ages’.