Abstract: In medieval China, Buddhism brought in new cultural genes. The remaking of knowledge and belief system deeply influenced the medieval political thought and practice in China. In the Buddha light, the political history of medieval China had its complex aspects, which are of significance for us to understand the world of knowledge, religions and politics in medieval China. In addition to the interactions between particular political figures or groups between particular Buddhist monks, sects, or monasteries, Buddhism's role in political history rooted in its fundamental ideas about the secular world, including its anticipation for a good world in the future and an ideal secular ruler and its discourse of ruling legitimacy. Buddhism puts political order in a divine and harmonious frame of reference, extends the sacred order of the universe to human beings and thus bestows the rulers with some necessity, certainty and eternity. Therefore, it is necessary for us to understand the political history of medieval China by taking account of Buddhist materials and religious logics.

Key words: medieval, Buddhism, political history, Cakravartin, ideology