534 (Ankan 1, 12th month): The Yamato court sends a military force to appoint Omi as the governor of Musashi Province, his rival, Wogi was executed by the court. Omi presented four districts of Musashi Province to the court as royal estates.
707 (Keiun 4): Copper was reported to have been found in Musashi province in the region which includes modern day Tokyo.
708 (Keiun 5): The era name was about to be changed to mark the accession of Empress Gemmei; but the choice of Wadō as the new nengō for this new reign became a way to 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".
May 5, 708 (Wadō 1, 11th day of the 4th month): A sample of the newly discovered Musashi copper was presented in Gemmei's Court where it was formally acknowledged as Japanese copper. The Wadō era is famous for the first Japanese coin (和同開珎, wadokaiho or wadokaichin).
Higashitama District (東多摩郡, Higashi-Tama-gun, "East Tama District") – part of Tokyo since its creation, merged with Minamitoshima District to become
Toyotama District (豊多摩郡) on April 1, 1896, in turn merged into Tokyo City in 1932
Kitatama District (北多摩郡, Kita-Tama-gun, "North Tama District") – was part of Kanagawa in 1878 until being transferred to Tokyo in 1893; North Tama's last
towns became [by definition: district-independent]
cities in 1970
Minamitama District (南多摩郡, Minami-Tama-gun, "South Tama District") – was part of Kanagawa in 1878 until being transferred to Tokyo in 1893; South Tama's last towns were turned into cities in 1971
Nishitama District (西多摩郡, Nishi-Tama-gun, "West Tama District") – was part of Kanagawa in 1878 until being transferred to Tokyo in 1893