[Grimmy]

An area depopulated by the sword then simply left fallow? or too much for any surviving locals to be able to clean up after?

[ConservativeMind]

I would think remaining locals would not trust remaining, because another raid could occur.

[SunkenCiv]

(spooky music)

[SunkenCiv]

An area depopulated by the sword then simply left fallow? or too much for any surviving locals to be able to clean up after?

Two things -- these are the remains found so far, and two, the rest of the population was probably carted off into slavery, not necessarily all that far. Ordinarily there would be fill-behind from neighboring areas, which is what happened a bit later. Looks like Copenhagen was a Roman territory, and used to control seagoing traffic and trade between the Baltic and the North Sea.

• Two Iron Age Sites Discovered in Finland | Popular Archaeology | Thursday, September 6, 2012 | unattributed | The other recently discovered site was located in Viirankoski, Loviisa. Based on the findings, the site has been dated to periods ranging through the Migration Period [4th & 5th c], the Merovingian Dynasty era [through the mid-8th c] and the Viking Age [8th through 11th c]. Similar objects have been found in Sweden in the areas of Lake Malaren, Birka and Göteborg. Several iron smelting furnaces, blacksmith forceps, hand- made ceramics and plenty of iron slag were uncovered at the site.
• New finds suggest Romans won big North Germany battle [ Harzhorn, reign of Maximinus Thrax, AD 235 ]