Humans have been around for a long time.  In Japan specifically, humans have been traced all the way back to prehistoric times.
Wow, that's interesting! About how long have humans been around?
Well as far as Japan goes, the first written account of the Japanese goes, there is a "Book of Han" which dates back to the 1st Century.
What is the "Book of Han" about?
It refers to the Han Dynasty or the Han Empire.  That was the 2nd Imperial Dynasty of China.
What was the first Imperial Dynasty of China?
I'm not sure but you could check in the "Records of the grand Historian" Which notes an early Dynasty around 2070 BC