Head family of a clan descended through the eldest sons (under the concubine system, legitimate eldest sons).
The concept of jongga originated in the code of clan regulations. The code of clan regulations is the logic that helps keep a kin group remain stable within a pyramid-shaped system; it is also a rule that prescribes where the legitimacy of the group is held. According to the code of clan regulations, an entire patrilineal kin group, that is, a lineage of eldest sons is called daejong (Kor. 대종, Chin. 大宗) and groups centered on each generation from the great-great-grandfather. That is, separated groups from the head family of daejong are called sojong (Kor. 소종, Chin. 小宗). The head family of daejong is referred to as daejongga and that of sojong, sojongga. Around the 16th century, the head family of a clan descended through its eldest sons began to be established, and by the 17th to 18th centuries served as a cultural model. Among the families descended through the eldest sons, only those admired by others are recognized as the head family.