I keep segregated playlists on my YouTube containing tracks that are thematic to the story I'm telling.

For Precipice of War, the longest running NRP I got I write through China. For that purpose I've since assembled a long playlist of generally traditional Chinese music on the pretense that it sounds like what'd play on state-controlled radio. When I go to write I may often put that on.

Likewise, I've had (keyword: had, most of the tracks on it have been removed from YouTube so while the playlist exists it's basically empty) one for classical music for when I wrote in a quasi-European Enlightenment setting for a fantasy RP set in that period. As well as for anything set in that RP.

More often though I've been drifting to Tibetan ritual music since it meets the criteria I need for writing. It's a background thing I can put on to mask other sounds while itself not being too distracted. Otherwise I might end up listening to the lyrics more than trying to put words to a page. Which is another thing too: if it has words I generally look for something in a language I don't speak or I have an incomplete lexicon of that language. So it tends to be strange obscure shit like Malian or Berber music, or Buddhist chanting.

[youtube]https://youtu.be/cDCS19EOsrA[/youtube]

Mantras or chants are helpful for background music too since they're fundamentally repetitive so there's nothing that pulls away your attention and allows you to slip into peace.

[youtube]https://youtu.be/2NoE8WwiqJc[/youtube]
[youtube]https://youtu.be/Tbj3ihvYEso[/youtube]