When MINAMOTO no Yoritomo established Kamakura bakufu (Japanese feudal government headed by a shogun), as a reward for military service Tokihiro YOKOYAMA from the Yokoyama Party received a fief and was approved as the landowner of the Yokoyama-sho estate.
源頼朝が鎌倉幕府を開くと、横山党の横山時広は軍功により横山庄の所領を安堵された。