Western Tokyo, known as the Tama area (多摩地域, Tama chiiki), Tama region (多摩地方, Tama-chihō) or toka (都下) locally, in the Tokyo Metropolis consists of 30 ordinary municipalities (cities (市 shi), towns (町 machi) and one village (村 mura)), unlike the eastern part which consists of 23 special wards.

[1] Before it was transferred to Tokyo in 1893, the Tama area, then also still often referred to as the "three Tama" (三多摩, san-Tama) (referring to the West, North and South Tama counties it consisted of) had formed the Northern part of Kanagawa Prefecture.

[2] Whereas in the east of Tokyo Metropolis the 23 special wards occupy the area that was formerly Tokyo City, the west consists of 30 other ordinary municipalities: cities (Nos.

The towns of Hinode, Mizuho, and Okutama, and the village of Hinohara make up the non-contiguous Nishitama District.

Under the Ritsuryō system, Western Tokyo was part of Musashi Province.