Here's one of those figures you see referred to as influences and mark down as subjects for investigation, though there's no time line attached when certain people's works are hard to find.
I've had A Rainbow in Curved Air and Church of Anthrax on the shopping list for a good forty years, what with the influence on the Soft Machine and the John Cale collaboration and all. But it has taken a while to happen across a copy of either.
American minimalist composer and performer Terry Riley is also the O'Riley in Baba O'Riley off Who's Next. He comes from a background steeped in jazz and Indian classical music. Spells at Shasta College, San Francisco State University, and the San Francisco Conservatory led to an MA in composition at the University of California, Berkeley. He worked with tape loops in the fifties, recorded with trumpeter Chet Baker and cites John Cage, John Coltrane, Miles Davis, Charles Mingus, Bill Evans and Gil Evans as influences on his work. That quintet of influential jazz figures are, in Riley's words described as leading "great chamber music groups."
The original plan involved a career as a concert pianist, and he paid his way through his studies by working as a ragtime pianist in a Berkeley saloon. There were also spells in Europe in the early sixties funded by playing piano in officers' clubs at US bases. An academic appointment to teach Indian classical music at Mills College in Oakland, California brought him into contact with Indian vocalist Pandit Pran Nath. Numerous trips to India to study and accompany the vocalist on tabla and tambura followed.
All those elements helped forge a compositional environment that incorporates strands of Indian raga, traditional Classical music, Western avant-garde, and American jazz filtered through a minimalist sensibility.
At least, that's the story as far as this non-expert can make out. Collaborations with the likes of the Kronos Quartet may follow, but first there are those items on the shopping list that need investigation.