What are they doing to prevent self-promotion spam?
The number 1 thing I want when listening to historical music, by the way, is a short written context. Example:
> This song was written by Werner Richard Heymann and Robert Gilbert for the 1930 musical film "Die Drei von der Tankstelle", and recorded by the Comedian Harmonists the same year.
> This choral recording from a church in Volda in 1955 was the final record published by His Master's Voice in Norway. It was a perennial favourite request for Ønskekonserten, a radio program where people could call in requests, in the following years.
I think it could likely be licensed like an internet radio, as you can't directly pick a song. I remember that back in the days it was very cheap to get this license, maybe 20 euros / month or so and you could just stream with your Icecast server legally (At least in Germany).
Pretty much a scatterplot of a few thousand genres, based on some Spotify labels. The full methodology is explained at the bottom of the page.