The castle grounds are protected as a National Historic Site by the Japanese government[1] The Yamagata Basin is a long and narrow inland valley of the Mogami River bounded by the Ōu Mountains to the east.

However, by the Sengoku period, the Mogami had lost much of heir power due to a succession of internal conflicts and short-lived leaders.

Taking advantage of the situation, Mogami Yoshimori regained his independence, and married his daughter to Date Terumune.

Mogami Yoshimori's eldest son, Mogami Yoshiaki fought many battle against various cadet branches of his own clan as well as the local warlords of many strongholds across Dewa Province from his base at Yamagata, with the Date clan sometimes assisting, but more often hindering his efforts to unit the province.

However, following an invasion by Uesugi Kagekatsu, who captured the Shōnai region, Yoshiaki was forced to submit to Toyotomi Hideyoshi.

The Mogami were rewarded after the establishment of the Tokugawa shogunate with an increase in territory to 570,000 koku with the recovery of the Shōnai region.

However, after the death of Yoshiaki in 1614, an internal conflict erupted between his major retainers, providing an excuse for attainder of the domain by the shogunate in 1622.

Renovations and archaeological investigations are ongoing, and Yamagata City plans to restore as much of the castle as possible to its early Edo-period condition by the year 2033.

The inner bailey is 200 meters square, was protected by clay walls and wet moats, and had gates at the southeast and north sides and a corner yagura.