First of all, what are these Ravens things (I love The Ravens), and is this to be taken as literally true, or is it one of those relative/appears to be so/AFAIK things?
"black vocal groups" of the '50s, in the '50s, maybe...the earliest live recordings that pop into my head are early '60s BUT I'm not an expert here. Would love to hear a good live recording of the '5' Royales or the Clovers or the Flamingos, to name just a few.