The founder, Shimazu Tadahisa (d. 1227), was a son of "Shōgun" Minamoto no Yoritomo (1147-1199) with the sister of Hiki Yoshikazu. Tadahisa's wife was a daughter of Koremune Hironobu, descendant of the Hata clan, whose name Tadahisa took at first. He received the domain of Shioda in Shinano Province in 1186 and was then named "shugo" of Satsuma Province. He sent Honda Sadachika to take possession of the province in his name and accompanied Yoritomo in his expedition to Mutsu in 1189. He went to Satsuma in 1196, subdued Hyūga and Ōsumi provinces, and built a castle in the Hyūga Province part of the Shimazu Estate, which name he also adopted.