Early period Prior to the
Asuka period, Dewa was inhabited by
Ainu or
Emishi tribes, and was effectively outside of the control of the
imperial dynasty.
Abe no Hirafu conquered the native
Emishi tribes at what are now the cities of Akita and Noshiro in 658 and established a fort on the
Mogami River. In 708 AD was created within Echigō Province. The area of Dewa District was roughly that of the modern Shōnai area of Yamagata Prefecture, and was gradually extended to the north as the Japanese pushed back the indigenous people of northern
Honshū. Dewa District was promoted to the status of a province () in 712 AD, and gained Okitama and Mogami Districts, formerly part of Mutsu Province. A number of military expeditions were sent to the area, with armed colonists forming settlements with wooden palisades across central Dewa in what is now the Shōnai area of
Yamagata Prefecture. The capital of the new province was initially established at Dewanosaku (出羽柵), a fortified settlement in what is now part of
Sakata, Yamagata, which served as a vital military stronghold in the expansion of Yamato control and settlement in the region. In 733, the capital was moved north, and a new military settlement, later named "
Akita Castle", was built what is now in the Takashimizu area of the city of Akita.
Abe no Yakamaro was sent as
Chinjufu-shōgun. In 737, a major military operation began to connect Akita Castle with
Taga Castle on the Pacific Coast. Over the next 50 years, additional fortifications were erected at Okachi in Dewa Province and Monofu in
Mutsu Province involving a force of over 5000 men. The road was greatly resented by the Emishi tribes, and after an uprising in 767, pacification expeditions were carried out in 776, 778, 794, 801 and 811. During the
Nara period, under the
Engishiki classification system, Dewa was ranked as a "greater country" (上国). Under the
ritsuryō system, Dewa was classed as a "far country" (遠国). The name of the province was originally pronounced "Idewa". The
Ichinomiya of Dewa Province was the
Chōkaisan Ōmonoimi Shrine in what is now
Yuza, Yamagata. During the
Heian period, in 878, a major rebellion known as the erupted in the region against Yamato rule. Another major uprising occurred in 939, as part of East Japan war
Tengyō no Ran. Towards the end of the Heian period, the province was organized into eleven districts. It was later a battleground in the
Gosannen War and the
Former Nine Years War.
Medieval period Following the destruction of the
Northern Fujiwara clan by the forces of the
Kamakura shogunate in 1189, many Fujiwara partisans fled to the mountains of Dewa and continued to resist central authority. The area was divided into numerous
shōen during the
Kamakura period, which developed into the centers of numerous rival samurai clans. In 1335,
Shiba Kaneyori received the Dewa Province as a fief from
Ashikaga Takauji, but ruled it only in name. By the end of the
Sengoku period, the
Mogami clan had emerged as the strongest local force in the southern portion of the province, whereas the
Akita clan dominated the northern portion of the province. Both clans sided with
Tokugawa Ieyasu at the
Battle of Sekigahara, and were thus secured in their holdings at the start of the
Tokugawa shogunate.
Early modern period During the early
Edo period, both the Mogami and the Akita were dispossessed, and their territories broken up into smaller
domains, the largest of which were held by the
Sakai clan and
Uesugi clans. During the
Bakumatsu period, all of the domains in the area joined the
Ōuetsu Reppan Dōmei supporting the Tokugawa shogunate. Following the defeat of the pro-Tokugawa forces, the new
Meiji government reorganized Dewa province into in the north, and in the south in 1868.These provinces became Akita Prefecture and Yamagata Prefecture on August 2, 1876. ==Historical districts==