Up until the reign of King Muyeol this aristocracy had been divided into "sacred bone" and "true bone" aristocrats, with the former differentiated by their eligibility to attain the kingship.
Indtil kong Muyeols styre var aristokratiet blevet opdelt i "hellig ben"- og "ægte ben"-aristokrater, med den førstenævnte udskilt ved deres berettigelse til at kunne opnå kongestillingen.