越中國
Toyama Castle is located at the center of modern current Toyama city. The surrounding area is roughly in the geographic center of Etchū Province and is a wide plain with a number of large rivers. A fortification was initially erected on this location in 1543 on the banks of the Jinzū River by the local Jinbō clan, who governed western Etchū Province as retainers of the Hatakeyama clan. Eastern Etchū Province was governed by their rivals, the Shiina clan, who were also retainers of the Hatakeyama. As the Hatakeyama waned in power and influence in the 15th century, the two clans waged a constant war for dominance over Etchū, with the "Ikkō-ikki" helping play one side against the other.