Brits singing re-packaged "race music" for Americans. Americans did try (see Pat Boone etc) but while the Beatles/Stones/Hermans Hermits dominated it was the rise of Motown that is most intriguing. Black Americans moving north for industrial jobs and having good wages finally put their music on the map. That it was playable on the radio for everybody (unlike the blues) was a masterstroke.
If you listen to the Beatles back catalog today it's pretty bad. Motown still sounds fresh.