Kōriyama originated as a regional governmental center in the
Nara period, when the area was on the frontier of
Yamato settlement of the Tōhoku region. The surrounding area developed into
shōen controlled by various samurai clans in the
Heian and
Kamakura periods. Nearby centers, such as
Nihonmatsu developed into
castle towns under
Hatakeyama clan and which were later controlled by the
Date clan, Kōriyama remained as a commercial center and thrived as a
post town because of its importance as a traffic focal point into the
Edo period and was part of the territory of
Nihonmatsu Domain. With the establishment of the modern municipalities system on April 1, 1889, the town of Kōriyama was established within
Asaka District. In the early
Meiji period, many dispossessed samurai were assigned undeveloped lands in the area to reclaim and as a result, the population grew and region developed into an agricultural center. The relative abundance of
hydroelectric power also helped with the development of local industry. Kōriyama was raised from town to city status on September 1, 1924 with the annexation of neighboring Odawara Village. Kuwano Village was likewise annexed on June 1, 1925. During the 1930s, Kōriyama was a noted center for military equipment production. It was thus a target for American bombers during
World War II, and the city was subject to three large-scale
air raids during the war. From 1954 to 1955, Kōriyama expanded by annexing the town of Otsuki and portions of the villages of Tomita and Iwae, and in 1965 annexed the villages of Nishida and Nakata. In 1997, the city received
core city designation, giving it increased autonomy from national and prefectural governments. On
March 11, 2011, the Great East Japan Earthquake caused damage, but Kōriyama is located outside of the mandatory evacuation zone set by the Japanese government after the
Fukushima Daiichi nuclear disaster. Many people from the evacuation zone relocated to Kōriyama. On 30 July 2020, a
shabu-shabu restaurant
exploded, damaging an area spanning several hundred meters. ==Geography and climate==