What is Scandinavian and Swedish traditional music?

The Nordic countries, that is Sweden, Denmark, Norway and Finland, have a lot of shared history and culture. When I talk about Scandinavian traditional music it is this shared aspects of the music cultures which  I alludes to. That is not to imply that there are not differences between them, but as it is possible to talk about 'Celtic' music as a general repertoire and style, I think it is possible to do the same with Scandinavia. My focus as a Swedish folk musician has been dance music, and to an extent herding tunes and folk songs. Although my main repertoire is Swedish, as most folk musicians in my generation, I have also played a lot of tunes from Norway, Denmark and Finland.
If I would think about one thing which to some degree connects this 'Scandinavian' music, I would say that the prevalence of pieces in various forms of three beat meter (3/4), which is much rarer on the British Isles. Although this is less pronounced in Denmark with its more continental connections and in Finland where there is both a Swedish influence and an older Finnish music tradition, the three beat meter is a reoccurring element which I often have to work with when teaching Scandinavian music in the UK.  At some point I will write a longer introduction to this area but if you are interested to learn more. I would recommend Dan Lundberg's introduction to Swedish folk music on the website of the Swedish Centre for Jazz and Folk Music Research.