I only know some western ones.

There are not many western classical schools that are sad, but there are many romantic schools and modern schools. Gnossienne No.1 by Satie and River Walts by Alexandre desplait are all very nice. You can check it online. These are probably from the 2th century, and they sound very melancholy.

In addition, Chopin is the first choice for piano. A lot of beautiful nocturnes are very sad. Rachmaninov's Piano Concerto No.2, Second Movement: Adagio continuo. Very nice! The melody that comes out of the tube at the beginning is touching and sad. And Beethoven ... Ha ha, I don't need to say these.

I really can't find China's. I'm really sorry. I hope these can help you, too. By the way, I think all my friends answered very well, so you can think about it ~hoho.