Personal Relationships of the Politicians related to the Division of East-West Party(1575) included in the Munhwa Yu clan's genealogy of 1565

As part of the study of the ruling class of the Joseon Dynasty, this article examines the personal relationships of the Sarim(Literati) faction politicians involved in the East-West division during the reign of King Seonjo. As basic data, blood relationship and marriage data from Munhwa Yu clan's genealogy of 1565, which can be said to be a comprehensive report of the ruling class of the time, was used. Through this, we tried to think about the background that led politicians who advocated Confucian ideal politics to seize political power with difficulty amidst frequent social conflicts, but which ultimately led to division. In particular, in order to derive objective analysis results rather than subjective interpretations, I selected the characters related to the EulhaedangRon (乙亥黨論) which was the beginning of the division as analysis target, and examined the cohesion structure that appeared in their personal relationships in networks and the possibility of sub-factions that could become the basis for division by quantitative methods. As a result of the analysis, it was found that the target characters shared commonalities as members of the ruling class, such as a closely intertwined marriage network, while some characters maintained even closer connections within this ruling class network. And it was judged that these, complemented by academic background and regionalism, were becoming a potential factors for making specific political and academic group in the future. I believe that a deeper interpretation can be derived through in-depth analysis of this in the future.