black horse
驪 centers on a black horse. It is a specific term for a horse with a dark coat.
驪 combines 馬 (horse) with 麗, which likely contributes the sound and may also suggest a glossy or beautiful quality, fitting a black horse. The exact historical development is uncertain.
A horse (馬) that is as dark and striking as a beautiful (麗) black coat: 驪 is a black horse.
For リ, imagine a black horse named Lee: Lee -> リ, and Lee is a sleek black horse.
—