For all periods of premodern Japanese literature, and indeed, for all premodern literatures, what survives is only a portion of the writings that were produced, but this situation is more extreme for the Nara and early Heian periods than for any subsequent point in Japanese history. Until the mid seventh century literacy remained the province of specialist scribes who were employed by the Yamato Kings, rulers from the area of modern Nara and Osaka who presided over a loose federation of local potentates spanning the archipelago from Northern Kyushu to the Kanto region. The importation of Buddhism in the mid to late sixth century introduced new kinds of texts and new modes of literacy, but these too remained narrow, specialized pursuits. The legitimacy of imperial rule by Tenmu's and Jito's successors was supported by a melange of symbols and rituals with complex origins. Similarly, early Japanese poetry and prose drew on a wide range of sources, foreign and domestic.