Iwamoto 【岩本】6 The Japanese surnames etymology dictionary.
② Topography . In Shimane-ken Hamada-shi tell her that she disliked the cow's saucer's sauce and turned it into a mountain and renamed it. Estimated in around the Warring States Period. It is unknown whether beef wood exists. Originated from the large mouth of Kagoshima-ken Isa-shi (old: cattle hut). A place name with a record since the Kamakura period. In the Muromachi Period, the place name was called "Ushiyamonin".