Craig Colbeck has written a
fascinating meditation on the problem of martial arts history.
Labeling karate a tradition relieves it of the obligations of a rigorous historicity; or rather, it establishes a distinct set of historical expectations. The relationship between tradition and history is problematic: by definition, every tradition needs a history, for legitimacy is founded in part on a recounting of origins, yet history is the description of change across time, which threatens the validity of a tradition.
I deal with martial arts history all the time: students who are current practitioners, or just consumers of popular culture, want to write papers and ask questions about it all the time. The main problem, as Colbeck notes, is the really weak quality of the pre-modern sources, leaving us with un-falsifiable myths; Colbeck's litany of questions which aren't really worth his time to answer about Karate is by itself worth the price of admission. His main conclusion, if I can distill it down without doing it great violence, is that Karate is as much of a modern invention as any martial art, at least the Japanese ones, all of which really are late-19c/early-20c inventions. It's much more interesting that I make it sound, and anyone interested in cultural essentialism (nationalism, cultural uniqueness, insider/outsider narratives) should spend the time to read Colbeck.