I've nearly finished Max Adam's 'The Last Kingdom' it's quite a long walk through the wavering marshes of the post-roman period and the beginning of the first Anglo Saxon kingdoms but worth reading for Mr Adam's has managed to synthesize together a lot of different information about this shadowy era and put it into an interesting, grounded narrative. You get the sense of the centuries 400-600ish being very dynamic for the communities living in Britain as they adapt to whatever comes next, and there being lots of possible kingdoms that never made it. Adam's talks about some very interesting things around the land and how the first kingdoms were organised around peripatetic kings with their followers who required special farms 'regia villae' within their territory to host them for a few months before moving on to the next. When it comes down to it all all these kingdoms could only exist with a peasant class who spent their days provisioning food, fuel and cloth for their lords.
