https://youtu.be/p9BnaJ4PyHE I often say that about stoner (rock)/doom (metal) and crossovers too. Russian circles sounds like stoner/doom to me as well. Here's another metal instrumental i dig (i like the ongoing groove): edit: lol only could paste it on top of post.
robocop reminded me of this one aka le parc tangerine dream https://www.youtube.com/watch?v=3Wu4agRHJUI
I like these two Native American Flute CDs I have, although I'm burnt out on one of them. I sometimes listen to instrumental mixes to read to or instrumental techno mix to study to One can search for these online.