The Aino people of northern Japan? Bearded, distinctly different facial features than other East Asian occupants, they appear more Caucasian than their neighbors. Perhaps a seafaring people who lost their urge to explore?
The Ainu are probably of the same group of refugees that fled Sundaland (an area the size of present day India) that went underwater at the end of the last Ice Age around Indonesia. The Melanesians (Negritos) have tales/stories/myths (Cain & Abel like) of tall, light-skinned, red-headed people in the region in prehistoric times.