The Bone System of the Three Kingdoms Period in Silla, Korean Peninsula

The Bone System, a strict social hierarchy based on blood ties that determined political and social status, was practiced in Silla, Korea, in the 4th century, when Silla unified all the ministries of the Tatsukan region by force of arms and established Gyeongju as its capital city. In order to consolidate its privileged position, the ruling group established a hierarchical system known as the "bone system". The Silla nobles had a hierarchical status and corresponding official rank according to their lineage, and no one was allowed to marry a person with a different bone rank. The bone rank was hereditary and remained unchanged. This system determines the degree of respect according to one's bone, i.e., hereditary lineage, and sets the maximum limit for holding an official position according to the different grades, and only those who have reached a certain grade of bone can be granted a certain official position, so one's career is governed by one's grade status in the bone system, and not only that, but the bone also determines the size of the residence that can be lived in by a resident of the Silla.

The ruling group of Silla consisted of the three royal families and the six nobles, and in order to consolidate their privileged position, the Joseon nobles of the big family names divided the class status of lineage and identity by the strict "bone system" for the purpose of "separate marriages," which was practiced with the remnants of the slavery system among the nobles of Silla. The "bone system" was practiced among the Silla nobles, which was a feudal system with remnants of slavery. The Park, Kim, and Seok families were the largest nobles in the ruling group of Silla, and not only could they inherit the throne, but they also dominated the entire bureaucracy and had supreme power. The three royal families of Park, Hsi, and Kim had the highest status and were called the "Sacred Bone" (the first bone), while the nobles of all sizes were divided into four classes, including the "True Bone" (or the second bone), the Sixth Bone, the Fifth Bone, and the Fourth Bone, etc. The "Sacred Bone" was the most powerful family in the Silla ruling group. The "Holy Bone" and "True Bone" nobles could inherit the throne. Each bone class is self-segregated and does not intermarry with each other.　

In addition, similar to the caste system in India, there are also various lower classes such as three-headed, two-headed, one-headed, commoners, slaves, and so on, which belong to the non-bone products.