Sometime between the third and seventh centuries, out of several rival clans in Japan, one emerged triumphant. The name by which they are known to history is Yamato, the ancestors of the Japanese imperial line.
Very little is known about the historical processes that took place to give power to the Yamato state, although some information has been learned from archeology. Instead the origins of the imperial line are contained in some very colourful legends written down as a series of creation myths when the emperor system had become well established.
These myths are preserved as Kojiki (The Record of Ancient Events) of 712 and the Nihongi (The Chronicles of Japan) of 720. The best-known myth, and the one that is fundamental to understanding the imperial cult, tells how Amaterasu the sun goddess founded the Japanese imperial line when she sent her grandson down from heaven to rule the 'land of luxuriant rice fields'.
The power of these early rulers is vividly illustrated in Japan to this day by the kofun, huge earthen tombs in which they were buried. They date from between the fourth and seventh centuries. They are often keyhole shaped and occupy a huge area of land. Nowadays the kofun are covered in trees, and some of the largest imperial tombs are islands in the middle of a lake. Armour, harness, weapons, bronze mirrors and jewels were buried along with the deceased and have been recovered from some of the tombs that have been excavated.
The actual origin of the dominant Yamato line is still a matter of some controversy. Based on similarities between the grave goods in the kofun tombs and contemporary Korean burials, a theory has been advanced that the first Japanese emperors came from Korea, and asserted their superiority in Japan through their use of mounted warfare, which had not yet been adopted by Japanese warriors. This is known as the 'horse-rider theory'. The notion calls into question the Japanese imperial line, let alone the first emperors' heavenly ancestors. It has therefore never been popular with Japanese nationalists.
Many challenges were made by rival clans against the dominance of the Yamato rulers. All were unsuccessful and, by the seventh century, the imperial line felt sufficiently secure to introduce far-reaching legislative changes for Japan. The Taika reforms of 646 were an ambitious set of edicts that sought to curtail any remaining power possessed by the other surviving clans by making all of Japan subject to the emperor.
One of the first tasks was creating a permanent capital city. This was achieved at Nara in 710. Buddhism, introduced to Japan two centuries earlier, flourished in the settled conditions of Nara. The government of Japan was modeled on Tang China and provided for a stable society. Any dissatisfied clans or trouble from the northern tribesman were dealt with efficiently. Kyoto succeeded Nara as the imperial capital of Japan in 894, a position it was to keep until 1868.