Keiun
708 (Keiun 5): The era name was changed to mark the beginning of the reign of Empress Gemmei; and Wadō as the new nengō mark the welcome discovery of copper in the Chichibu District of what is now Saitama Prefecture.  The Japanese word for copper is dō (銅); and since this was indigenous copper, the "wa" (the ancient Chinese term for Japan) could be combined with the "dō" (copper) to create a new composite term — "wadō" — meaning "Japanese copper."