Sotan tried to control the Shimazu clan, which was extending its influence in the ascendant in Kyushu at that time, as well as to enhance his position as a wealthy merchant by having Nobunaga's protection.
宗湛は信長の保護を得ることで、当時九州で日の出の勢いで勢力を拡大していた島津氏を抑えるとともに、豪商としての地位をさらに極めようとした。