Why are bears called Yai Guai?

This always confused the hell out of me. I know its Chinese but normally when we borrow a word, it is because it doesn't already exist in the native language. English has a word for bear! Why would people stop calling bears, bears, and start calling them this new Chinese name.

This gets even more confusing on the west coast from a Fallout 3, Fallout 4, and Fallout 76 viewpoint, there aren't a lot of Chinese citizens to share the word.