When Was Japan Born?

I think if you drop in at this blog, you will probably be one who may be interested in Japan or other Asian countries. I happened to see the Japan page, NY times, I knew that I hadn't known
the birth(or independence) year of Japan. Here's the page;

Japan at a Glance

Official Name: Japan

Capital: Tokyo (Current local time)

Government Type: Constitutional monarchy with a parliamentary government

Chief of State: Emperor Akihito represented by Yukio Hatoyama, prime minister

Population: 127.43 million

Area: 145,902 square miles; slightly smaller than California

GDP Per Capita: $33,100

Year of Independence: 660 B.C.

Since I saw "Year of Independence" here, I haven't known what year Japan became dependent. In fact I can't remember if I learned at school when Japan appeared in the world history. At the beginning of the histry class that most Japanese people have, the origin of the Old World is first introduced and after that the dawn of Japan is introduced, but never is that Japan was born in 660 B.C. taught! We just learned that early Japanese used stone tool at that age.

What's "the Year of Independence, 660 B.C."? To be sure, it comes from part of the Nihon Shoki, and Wiki says,

"Most scholars agree that the purported founding date of Japan (660 BC) and the earliest emperors of Japan are legendary or mythical."