I only recently found out about The Kim Sisters. They were a South Korean trio who had a successful career in America during the 50's and 60's. To support their family during the Korean War, they performed songs for American GIs who then spread word of them after returning home. They were signed to a contract and went to the US, eventually performing 22 times on The Ed Sullivan Show.
For a Korean American like me, who grew up in parts of the US where I was the only Asian kid in school, it's pretty astonishing to discover Korean performers who were successful in the US at such an early time. Even more impressive is the fact that they sang in English.
Eventually they performed with their brothers who had their own group. Check out the great performance with The Kim Brothers in the video below at 4:26.
I asked my father about them and he explained that their mother, Lee Nan-young (이난영), was one of the most famous singers in Korea at the time, and that in Korea she is even better known than the sisters are. Here is one of her songs.