Yes, in Japan, the clan or party system was indeed a fundamental aspect of social, religious, and political organization, particularly in ancient and medieval times. The term commonly used to refer to these clans is "uji," which were extended families or kinship groups that played significant roles in society.
These clans were not only family groups but also formed the basis of social structure, with each clan having its own deity, governance structures, and roles in religious practices. Politically, clans were crucial in the formation of early Japanese states, such as during the Yamato period, where powerful clans held political authority and often competed for power and influence.
In the context of the samurai era and feudal Japan, powerful clans like the Minamoto and Taira were central to political machinations, forming the backdrop for events such as the Genpei War. Over time, the importance of individual clans shifted, especially with the rise of the shogunate and the centralization of power under the emperor and shoguns.
Overall, these clan systems shaped the historical, cultural, and societal landscape of Japan for centuries.