The Mikuni kaidō was an important road connecting Echigo with the Kantō area, and the modern Kan-Etsu Expressway and the Jōetsu Shinkansen still utilise this route.

However, the Uesugi preferred to remain new the centre of political power and assigned the province to the Nagao clan to rule as deputy governors.

Sakado Castle, as was common with mountain-top fortifications of the time, consisted of many narrow terraces (kuruwa) spread across several levels on the side of the mountain.

Under the Muromachi shogunate, the Uesugi clan was appointed to the post of Kantō Kanrei, but through continuous warfare their situation was greatly weakened.

On his death in 1543, his son Nagao Harukage was unable to hold the clan together, and turned authority over to his brother, Kagetora, later known as Uesugi Kenshin.

[2] Kagekatsu was supported by Kenshin's closest guards and quickly captured Kasugayama Castle and the Ueda-Nagao rallied to his banner.

However, Kagetora had the support of the most important retainers as well as backing by the Takeda and Hōjō clans, and isolated Kasugayama Castle from the Uonuma basin.

Unable to fight a war on two fronts, Kagekatsu quickly made a separate peace with the Takeda; however, the Hojo were able to lay siege to many of the border castles in the Uonuma region, including Sakado.

At the foot of the mountain is the Nagao Masakage Cemetery and a monument proclaiming the area to be the birthplace of Uesugi Kagekatsu and Naoe Kanetsugu.