Worldbuilding with Music: Ursula K. LeGuin was a visionary
Characters, worlds, and civilizations do not spring like whole cloth from the minds of their creators. It is the secret folly of every world builder that we have hidden away in a deep, dark drawer, notebooks full of character outlines, histories, music, poetry, and maps. (My drawer, if we were to battle the spiders who hold it hostage, contains maps covered in scribbled equations that equate the gate of giant elk to the distance and time it takes to travel the long distances between domes. I even have a genetic map of the evolution of a planet full of psychically connected flora and fauna and the chemical formulas for bloodstones and cyanide venom.)
J. R. R. Tolkein's estate put his notebooks into their own book and called it Silmarillion which became a huge source for Peter Jackson as he was fleshing out the movies. This is the source of the Elven language he created.
J.K. Rowling's notes on her world building can be found in bits and snippets on the internet and on her websites. There is Tales of Beedle the Bard, of course, but my favorite is the genealogy of Harry Potter that traces his ancestry back to the three brothers and the origins of the Hallows.
Ursula K. Le Guin went one step further. Her gift at world building was extraordinary and it is reflected in her stories. For example, she wrote a novel called Always Coming Home about the Kesh, a tribe living in Northern California in the distant future. This was 1985, long before the internet took over the airwaves. Ursula, with the help of a musical friend, recorded an album called Music and Poetry of the Kesh made up of poetry, songs, and teaching stories of the tribe. https://futurism.com/sci-fi-novelist-ursula-k-le-guin-album/
Ursula died this past January and the world is a lesser place with her passing. Grand Master of Science Fiction, they called her in the end but she hated being shoved into such a small genre. She considered herself a novelist, first and foremost, like Margaret Atwood. Of the two female speculative fiction writers, their Wikipedia pages are almost identical except for the fact that Atwood is Canadian and Le Guin was American. Le Guin's awards are all in science fiction. Atwood's awards are for Literature. The American market place is brutally bigoted when it comes to anything that has the slightest stink of fantasy and make-believe. The English, on the other hand have embraced their scifi writers, repackaging them as satirists or writers of speculative fiction as far back as Johnathan Swift and Mary Shelley.
If you want to get a taste for Ursula K. Le Guin's talent as a world builder read her short stories. It is a true gift, to build a world full of depth, emotion, and thought provoking ideas in under 5,000 words. Reading a Le Guin short story is like sipping fine aged wine. One glass is enough to fill your mind with the perfume of her intricate mind. The whole bottle would be overkill.