Pre-Roman Iron Age in North Europe?

Scott wrote on the Bladesmith's Forum:

I have a hard time piecing together the history of Europe in the early Iron Age... Pre-Roman.   I get that east and north were generally Germanic and to the west was mostly Celtic.   I see plenty of examples of Celtic swords and I see the single edge Germanic swords and war knives.. and I know that the Germanic tribes adopted Roman swords at some point.. but what double edge swords were of pure Germanic origin .. if any?

Another thing I'm curious about but see very little in the literature is the nature of interaction between the Celts and Germans.  Obviously it was either trade or war ... but what details and evidence?  Obviously there would have been no written account until the Romans became involved.  But what does archaeology tell us?

If you define 'Iron Age' as 'marking the use of iron as material' - then the true Iron Age runs from at least about 1000 BC in Northern Europe.

One of the other definition problems is that mainland Europeans / British / Scandinavians all see the frame work of their own past marked by different events. So much of what us English speakers have access to is from Britain. The line between 'before the Celts' and after this invasion is fuzzy at best, and does appear to also mark the transition from a primary Bronze Age into the early Iron Age. The Roman period has sharp lines for initial start and theoretical end.  Then there is another fuzzy period around the 'Saxon Shores', when the 'Germanic' Angles and Saxons are invading and colonizing.
Complicating this is the whole very modern concept of national boarders. I mean, does a person living in North west France about 200 AD part of 'French' or 'Celtic' or 'Gallish'  culture? (Or maybe even some weird mix of Roman plus all of the above?)

Part of a big problem for me is the whole concept of the 'Viking Age', which is defined by two British only events : Lindesfarne in 783 and (usually) the Norman invasion of 1066. Some argument at least can be made for an end to the true Viking Age some place about 1000 - 1100, with the growth of centralized kingdoms and gradual adoption of a more feudal structure. The notion that the Scandinavian culture sprung to life fully formed overnight is obviously unrealistic!

I was a bit surprised when I managed my one trip to Denmark that there they break the lines at 'Iron Age' to 1000 AD and then 'Medieval', running afterword. (I guess I should not have been!). North Germany and Denmark into Scandinavia was relatively untouched by Roman culture (quite unlike the rest of Europe).

Some histories out of mainland Europe will mark 'Migration Period', which usually is some (again fuzzy) time 'post Roman - pre Medieval'.  This is at least a bit better than the older seen line of 'Roman to Medieval', given as the 'Dark Ages'. (Honesly, I'm never quite sure just when that is supposed to cover - at least in terms of end dates.)

'Migration Era' grave goods set - fighting knife and small tool knife

(left) 'Celtic Iron Age' - c 100 BC
Iron sword locked into decorated bronze scabbard with cast bronze fittings.

If your interest is clearly on * object *, your best bet might be just digging into the archaeological record. Not a simple task, as you are unlikely to find a single point reference that is going to help you. Its going to be a tedious task of checking dates and find locations.
One of the huge problem is one of simple survival of iron objects. The Celts of La Tene are a primary * Iron Age * culture. But what do we find? Bronze objects! Iron swords corroded and locked into decorative bronze scabbards, with only rare x-rays giving any clue at all about physical structure of the blades.

Complicating this is the whole modern tendency to apply our current 'best technical practice' backwards. 'Steel' means something quite different when applied as a descriptor by an archaeologist to an Iron Age blade - than it means to a modern bladesmith.  Original bloomery iron materials most often had little or no carbon - and also have a quite different physical structure from our modern alloys. It is clear when you look at primary archaeological reports that our current practices of heat treating were only being developed and more randomly applied through the 'Late Iron Age'.

See also some earlier posts:
'Iron from Celtic to Early Medieval'
'Iron Age vs Viking Age'

Exploring the Viking Age in Denmark