Yonezawa Domain
The area of present-day Nagai was part of Dewa Province and was part of the holdings of Yonezawa Domain under the Edo period Tokugawa shogunate. The village of Nagai was created within Nishiokitama District, Yamagata with the establishment of the modern municipalities system on April 1, 1889. Nagai merged with the neighboring villages of Toyoda, Hirano, Nishine and Isazawa on November 15, 1954 to form the city of Nagai.