We shall now turn our attention to the remarkable political evolution which followed and was in fact to a large extent occasioned by the introduction of Buddhism. In the earliest days of the empire, administrative posts were transmitted by heredity from generation to generation. It thus resulted that family names were derived from official titles, as, for example, the official title for persons performing religious rites was Nakatomi or Imbe, which titles became family names of holders of that office. Similarly Ōtomo and Mononobe were family names of officials having control of troops or direction of military affairs. Among commoners, also, there were many who performed certain kinds of work for the government, the art of which they bequeathed to their children by heredity. Each occupation of this description was organized into a guild, and each guild was under the control of a headman who belonged to some influential family. Not only were public offices and private guilds similarly organized by the principle of heredity, but also there was no rigid line drawn between the public property and the personal possession of a nobleman. The higher one's position among the aristocracy, the more exalted was his office and the more plenteous his treasury. Under these circumstances, it is not strange that the administration of the state gradually fell under the control of the heads of a few powerful clans. Originally, during the reign of the first emperor, the Nakatomi and Imbe families discharged religious functions, and the Ōtomo, Kume, and Mononobe families performed military duties. The influence of these families was then about equal. But subsequent events resulted in the decline of the Kume, while the Ōtomo were in the main intrusted with the control of Korean affairs. Domestic administration remained chiefly in the hands of the Mononobe and the new family of Soga, descendants of Takenouchi, the tactful minister of the Empress Jingō. The Mononobe stood at the head of all the noble families bearing the honorary title of Muraji, and the Soga, of those likewise designated as Omi. It was inevitable that the mutual jealousy of the two leading houses should bring them to a clash of interests, while the introduction of Buddhism had the effect of greatly accentuating their hostility. It will be remembered that the Mononobe family adhered steadily to conservative principles and opposed the spread of Buddhism, which the Soga, on the contrary, zealously upheld. So long, however, as both families bowed implicitly to the imperial commands, their dispute did not attain serious proportions. But when, in the reign of Yōmei, not only was the empress dowager a daughter of the Soga family, but also the emperor himself inclined to the worship of Buddha, the final struggle between the two families could no longer be deferred.