Stone ships had been burial sites for two thousand years before the Vikings came to Lindisfarne. And long distance trade has been established and given the extent of the Battle of Tollense contact between tribes must have stretched far and deep. And Britain was an important source of tin so trade routes both started and ended there.
Two thousand years! I thought of the stone ships too (these are burials marked by stones laid out in the shape of a ship), but I went searching for an old example and it seemed like the oldest persuasively dated one is from around 600.
Tjelvar on Gotland are presumed to be from 750BCE, and I don't think that is the oldest in Scandinavia.
Oh, nice. That's the one I couldn't find a Wikipedia article on, though I see now it's mentioned under Boge (with a picture). https://en.wikipedia.org/wiki/Boge,_Gotland