As of October 2013, the district has an estimated population of 41,272 and an area of 796.26 km2.
Murayama County was an ancient place name in part of Dewa Province, occupying the area of modern Mogami, Kitamurayama, Higashimurayama and Nishimurayama districts.
Under the Tokugawa shogunate, the area of Nishimurayama district was a complicated mosaic.
At that time, Nishimurayama District consisted of 125 villages.
With the establishment of the municipality system on April 1, 1889, the district was consolidated into 21 villages.
Map showing original extent of Nishimurayama District in Yamagata Prefecture
yellow & green area=original extent in Meiji period; green=present area; 1=Kahoku, 2=Nishikawa, 3=Asahi, 4= Ōe
Historic Map of Nishimurayama District:
Sagae
Nishine
Shibahashi
Takamatsu
Aterazawa
Ōtani
Nishi-Imogawa
Higashi-Imogawa
Hongo
Shichiken
Ōizawa
Hondoji
Kawadoi
Nishiyama
Shiraiwa
Daigo
Nishisato
Miizumi
Mizonobe
Yachi
Kita-Yachi
Tamano
Tokiwa
Purple=Sagae City
Yellow= Nishikawa Town
Orange= Ōe Town
Red=Kahoku Town
Pink=Asahi Town
Blue=to Shirataka Town