Around the 3rd. century, "Yamato" dynasty united Japan.
"Kojiki" and "Nihon Shoki" describe the tale of the origin of "Yamato" dynasty as mythology.
The Gishi-Wajin-Den, official history of China, described a couple of nations, called "Kuni", existed in Japan in the third century. Yama-tai koku, was led by "Himiko" who was the leader of "Kuni"s.
It is a big discussion where Yama-tai koku were located. Some said in norther Kyushu and some said in Kansai.
It seems that there were a couple of nations located in Kyushu, Kansai and also Izumo, Okayama area.
Then finally, the Yamato dynasty united Japan. The Yamato dynasty was located in the Kansai area.
In this period of time, leaders of the Yamato dynasty were buried in a huge ancient tomb.
Traditional shrines remain from this age.
An excellent example is Ise Shrine.