In his Many Thousands Gone, James Baldwin wrote
We cannot, to begin with, divorce this book from the specific social climate of that time; it was one of the last of all through the thirties, dealing with the inequities of the social structure of America. It was published one year before our entry into the last world war–which is to say, very few years after the dissolution of the WPA and the end of the New Deal and at time when bread lines and soup kitchens and bloody industrial battles were bright in everyone’s memory. The rigors of that unexpected time filled us not only with a genuinely bewildered and despairing idealism–so that, because there at least was something to fight for, young men went off to die in Spain–but also with a genuinely bewildered self-consciousness. The Negro, who had been during the magnificent twenties a passionate and delightful primitive, now became, as one of the things we were most self-conscious about, our most oppressed minority. In the thirties, swallowing Marx whole, we discovered the Worker and realized–I should think with some relief–that the aims of the Worker and the aims of the Negro were one. This theorem to which we shall return–seems now to leave rather too much out of account; it became, nevertheless, one of the slogans of the “class struggle” and the gospel of the New Negro.
I am especially interested in the part indicated in bold. What is he referring to by the "magnificent twenties"? Apparently, there was a change of attitude towards the black community. Can anybody explain this to me? Thank you!