So I've been flicking through the relevant sections of Dark Age Economics: the origins of towns and trade AD 600 - 1000 by Richard Hodges all day and it's just way too dense. My mind is mush and I've only been able to gleam the definitions that archaeologists give to determine what a town is (page 21) and that the Viking raids from 840-870 forced the need for "centralised leadership" and that burhs were a military strategy to quell the Vikings (page 159).
You're probably better off with Hodges' DAE: A new audit (2012) or some of Søren Sindbæks work, such as Networks and nodal points (2007). Hodges' early work, while fundamental, was still way too much coloured by an evolutionary view of the development of urbanism, while the modern view of urbanism (or proto-urbanism) is quite a bit more nuanced.