Hyeokgeose is said to have been hatched from an egg laid from a white horse, and when he turned 13, six clans submitted to him as king and established Saro-guk (also called Seona).
Hyeokgeose siges at stamme fra et æg lagt af en hvid hest, og da han fyldte 13, udpegede seks klaner ham til konge og etablerede Saro (eller Seona).