霓裳 is most famous as part of
霓裳羽衣曲 (níshang yǔyī qǔ) — 'Rainbow Feather Garment Melody' — a celebrated Tang dynasty court composition. According to legend, Emperor Xuanzong composed it after dreaming of the Moon Palace. The song became synonymous with the beauty of the Tang court and Yang Guifei, his beloved consort.