Shō Hashi
Historian Wada Hisanori notes that the "Rekidai Hōan" contains diplomatic documents supposedly sent by Taromai, King of Sannan. Wada speculates that Shō Hashi, the unifier of Okinawa Island, had already kept Sannan under his control. According to his hypothesis, Taromai was the eldest son of Shō Hashi while Ōōso was either a pseudonym of Shō Hashi or his puppet ruler. Shō Hashi gave southern Okinawa to the first son while the rule of northern Okinawa was left to his second son Shō Chū.