The Yamato state was the polity centered on the Nara basin of central Japan that took shape gradually across the third and fourth centuries CE, rising from one strong chiefdom among many into the ruling power of the archipelago. It governed through hereditary clans and hereditary service groups, absorbed Buddhism and Chinese models of law and office, and by the early eighth century had transformed itself into a law-governed classical state rather than disappearing, moving to a permanent capital at Nara in 710. The later imperial house claimed descent from, and likely developed out of, its ruling line, though a continuous genealogy before the sixth century is not securely documented.
In 1968 archaeologists opened a burial mound at Inariyama, on the Kantō plain far to the east of Nara, and lifted out a corroded iron sword. Ten years later an X-ray found what the rust had hidden: 115 Chinese characters inlaid in gold, listing a warrior's ancestors back seven generations and naming the lord he had served. The lord was a Great King called Wakatakeru, and the date on the blade is most often read as the year 471. The sword is widely interpreted as evidence that a ruler seated in the Nara basin held the loyalty of a fighting man buried hundreds of kilometres away, and that someone in that provincial household could write. The kings of Yamato left almost nothing in their own words. Their servants, now and then, left it for them.