The area of present-day Sagae was part of ancient
Dewa Province, and has been settled since prehistoric times, with numerous archaeological findings from the
Japanese Paleolithic through the
Kofun periods. In the late
Heian through
Kamakura periods, it was a
shōen under the control of the
Ōe clan. The Ōe were destroyed by the
Mogami clan in the
Sengoku period, who were in turn destroyed by the
Tokugawa shogunate in the early
Edo period. The territory was administered as
tenryō under direct control of the shogunate until the
Meiji Restoration, and was briefly a battleground in the
Boshin War. After the start of the
Meiji period, the area became part of
Nishimurayama District, Yamagata Prefecture. The village of Sagae was established on April 1, 1889, with the creation of the modern municipalities system, and was raised to town status on January 7, 1893. It became a city on August 1, 1954. ==Government==