The Asinas of Aizu, a Miura clan from Sagami (Kanagawa Prefecture), were the retainers of Minamoto no Yoritomo, who established the Kamakura shogunate in 1192, and acquired a fief mainly in the northern part of Aizu, the breadbasket region of Aizu, through their great military success.
The 16th Moriji, who built the heyday of the Ashina clan, was the most powerful of the clan at the height of the Warring States period. He was the founder of the Reed family, and was known as the “Taishu of Aizu” with one million koku (one million koku). It was Moriji who built Mukaihaguroyama Castle over a period of eight years.
However, Morioji’s heir apparent, Moriooki, the 17th, died of illness at the young age of 29 in 1574, leaving no heir. Morioji’s wife (Date Ujime) was given as a son-in-law Nikaido Moritaka, a hostage from Sukagawa, to succeed to the Asina family, but he was slain by a vassal, and his son Kamewaka (Ou) Maru also died of illness at a young age.
Moriji was at the height of his power, but after his death in Tensho 8 at the age of 60, the family was disturbed by the subsequent issue of adoption, and in the fateful battle of Suriagehara at the foot of Mount Bandai in 1589, he was defeated by Date Masamune, putting an end to his 400-year rule of Aizu.