english ILMers: explain the term "northern soul"

I've always been somewhat befuddled by the term. why
are mostly obscure American soul artists/singles from the '60s and '70s
referred to as such? because a bunch of pilled-up mods from the north
of england championed them? if I bought and hoarded a bunch of
Indonesian gamelan records, and then a bunch of my fellow new yorkers
did the same, and we had parties where we danced and listened to them,
could we call it "New york gamelan"?

what am I missing? can any english people explain this?