The Ritsuryo system (a Japanese historical law system) in Japan includes a national ideology that can be referred to as the Japanese-barbarian dichotomy and which overlaps with the Sino-barbarian dichotomy in China. Within the framework, the Emishi and Hayato tribes were regarded as barbarians, outside of the control of Japanese Emperors and the polity. Nevertheless, these tribes offered tributes and paid homage to Japanese Emperors, who fostered them by use of feasting and donations, and conducted military strikes in cases of resistance. Although these tribes were integrated into the Kokugun system (a historical Japanese system of local administrative divisions), during the centralization of the ancient Japanese polity, the Emishi frequently resisted up until the Heian period. As a result, the polity provided focused a number of political measures on this tribe. In this context, one unique archaeological phenomenon, the fact that the roofs of both the Kanga (the local administration office) in Mutsunokuni Province adjacent to the Emishi tribe and Buddhist temples in this region were covered by the same type of roof tiles provides evidence for one such political measure. The authority of the polity against the Emishi tribe was manifest not just in military campaigns, as previously noted, but also by the use of roof tiles at Kanga as a place of polity control and in temples as places of Buddhization. These lines of evidence suggest that political concepts in ancient Japan included rule by virtue of the philosophy of Imperial Influence imported from China associated with the Sino-barbarian dichotomy.