Welsh legend says that Corgis were gifted to humans by fairies.

According to Welsh folklore, fairies once rode Corgis the way that cowboys ride horses. The sprites apparently liked to use the tiny canines to pull their carts and carriages around, and would sometimes ride the dogs into battle. Most versions of the legend typically include the fact that the fairies gifted the Corgis to human children, which is how the dogs made their way into the mortal realm.
https://thesmartcanine.com/corgis-and-fairies/