According to Japanese legend, Japan was discovered by Nigini no Mikoto, who was sent to the region by the Sun goddess Amaterasu to establish rule. His grandson, Jimmu, became emperor in 660 B.C. Jimmu is considered the first Emperor of Japan.
Amaterasu-omikami is a Shinto goddess who is considered the ancestor of the Japanese Imperial family. Her grandson Nigini no Mikoto was given a set of jewels, a sword and a mirror to take with him when he established the Japanese monarchy. As of 2014, the mirror is still in the inner sanctum of Ise Shrine in Mie Prefecture.
Much of Japan's earliest history is only known as legend. The recorded history of the country became more established during the reign of Emperor Keitai from 507 to 531 A.D.