How long has Japan been a Country?

Question:

^^

Answer:

Before the advent of the Yama Taikoku in the 3rd century, the history of Japan as a country is not clear. According to multiple Chinese documents, a regional nation (probably in Kyushu) called "Wa" had close contacts with China long before the Yama Taikoku. However, it was not a country by today's definition.

Some Japanese 'documents' (I hesitate to call them so, because they are no more than a fabricated prehistorical mythology written in as late as 8th century) describe the origin of Japan from the first Emperor Jinmu. But, there is no historical authenticity until the 10th Emperor Sujin. Japanese mythology is a fascinating story for us Japanese, but, its historical authenticity is very dubious.

So, I would say the country of Japan with a political structure was created in the 3rd century.