| 4.233 million (1 Oct 2016)|
Western Tokyo, also known as the Tama area (多摩地域, Tama chiiki), Tama region (多摩地方, Tama-chihō) or toka (都下), consists of the part of Tokyo Prefecture to the west of the 23 special wards.
Whereas the special wards occupy the space that was formerly the city of Tokyo, western Tokyo consists of 26 cities, three towns, and one village occupying the area that were not part of the former city. They serve as "bed towns" for those working in central Tokyo, although some of them have a local commercial and industrial base.
The towns of Hinode, Mizuho, Okutama, and the village of Hinohara lie in Nishitama District.
The offshore islands of Tokyo (including the Bonin, Volcano, Izu island chains, and the uninhabited islands of Okinotorishima and Minamitorishima) are not considered part of Western Tokyo.
Under the Ritsuryō system, Western Tokyo was part of Musashi Province. The provincial capital was at Fuchū. The provincial temple (kokubunji) was at Kokubunji and the principal shrine (ichinomiya) was at Tama.
Western Tokyo previously consisted of three districts:Nishi-Tama District (西多摩郡, Nishi-Tama-gun) (lit. "Western Tama") encompassed the present-day cities of Akiruno, Fussa, Hamura, and Ōme; in addition to the four municipalities (3 towns and a village) that still remain a part of the district.
Minami-Tama District (南多摩郡, Minami-Tama-gun) (lit. "Southern Tama") covered the area now occupied by Hachiōji, Hino, Inagi, Tama, and Machida. With the formation of Inagi (the last city to be created in Tokyo in 1971), Minamitama District ceased to exist.
Kita-Tama District (北多摩郡, Kita-Tama-gun) (lit. "Northern Tama") consisted of the locations of the present-day cities of Akishima, Chōfu, Fuchū, Higashikurume, Higashimurayama, Higashiyamato, Kiyose, Kodaira, Koganei, Kokubunji, Komae, Kunitachi, Mitaka, Musashimurayama, Musashino, Nishitokyo, and Tachikawa, as well as some land now in Setagaya. With the establishment of the city of Musashimurayama in 1970, Kitatama District ceased to exist.
Western Tokyo Wikipedia