The Heian period in Japan, from 794 to 1185 CE, began with the relocation of the capital to Heian-kyō (modern Kyoto). Political power initially shifted to the Fujiwara clan through strategic intermarriage with the imperial family. A smallpox epidemic between 812 and 814 CE severely impacted the population, killing nearly half of the Japanese people. By the late 9th century, the Fujiwara clan had solidified their control. Fujiwara no Yoshifusa became sesshō ("regent") to an underage emperor in 858, and his son Fujiwara no Mototsune later created the office of kampaku, effectively ruling on behalf of adult emperors. This period saw the height of Fujiwara power, especially under Fujiwara no Michinaga, who became kampaku in 996 and married his daughters into the imperial family. This dominance lasted until 1086, when the practice of cloistered rule was established by Emperor Shirakawa.

As the Heian period progressed, the imperial court's power waned. Engrossed in internal power struggles and artistic pursuits, the court neglected governance beyond the capital. This led to the decay of the ritsuryō state and the rise of tax-exempt shōen manors owned by noble families and religious orders. By the 11th century, these manors controlled more land than the central government, depriving it of revenue and leading to the creation of private armies of samurai warriors.

The early Heian period also saw efforts to consolidate control over the Emishi people in northern Honshu. The title of seii tai-shōgun was granted to military commanders who successfully subjugated these indigenous groups. This control was challenged in the mid-11th century by the Abe clan, leading to wars and eventual reassertion of central authority in the north, albeit temporarily.

In the late Heian period, around 1156, a succession dispute led to military involvement by the Taira and Minamoto clans. This culminated in the Genpei War (1180–1185), ending with the defeat of the Taira clan and the establishment of the Kamakura Shogunate under Minamoto no Yoritomo, effectively shifting the center of power away from the imperial court.