 Thus, succeeding his father as chief of Chūzan in 1422, and appointing his younger brother Warden of Hokuzan, he seized Nanzan Castle, capital of Nanzan, in 1429, from Lord Taromai.Thus uniting the island of Okinawa, he founded the Ryūkyū Kingdom and the Shō Dynasty.Up to this point, the three polities had operated on a very simple feudal model.