Chinese Influences: The Japanese were forced out of the Korean peninsula in the sixth century, but not before the Koreans had bequeathed to the Yamato court copies of the sacred images and scriptures of Chinese Buddhism. Just as Christianity introduced Mediterranean culture into northern Europe, so Buddhism brought Chinese culture into Japanese society. Throughout the seventh and eighth centuries numerous Japanese monks, scholars, and artists made the perilous trip west across the Sea of Japan to study Chinese religion, history, music, literature, and painting — later to be brought back for further development in Japan. An outstanding figure of this time was Prince Shotoku, who in 604 developed the "Seventeen-Article Constitution," outlining a code of human conduct and the ideals of state as a basic law for the nation. He also established relations with the Sui dynasty in China. Through him, the Japanese imperial court developed Chinese patterns of centralized government, with its formal bureaucracy of eight court ranks. The Chinese calendar was used to calculate the year of Japan's foundation by counting back the 1,260 years of the Chinese cosmological cycle. Thus, 660 b.c. is still the official date celebrated nationwide. At this early stage in its history Japan was already (for the most part) only nominally ruled by the emperor. De facto power was exercised by the militarily and economically strongest family. The Sogas had promoted Buddhism as an imperially sanctioned counterweight to the native Shinto religion, along with the new Chinese customs, to weaken the influence of their more conservative rivals. But they in turn were ousted in a.d. 645 by Nakatomi Kamatari, founder of the great Fujiwara clan, which was to rule Japanese affairs for hundreds of years and provide prominent advisers to the emperor even up to the 19th century. 
What year was Japan founded
660 A.C