 According to the "Samguk Sagi", the Goguryeo royal family claimed descent from the mythical god Gao Yang, who was the grandson of the Yellow Emperor of Chinese mythology, and thus took the surname of "Go" (高); however, this legend was discredited in the commentaries () by Kim Busik, the compiler of the "Samguk Sagi", who concluded that both Baekje and Goguryeo originated from Buyeo.Goguryeo's height of power came in the reign of Taewang Gwanggaeto the Great of Goguryeo, who created and strengthened Goguryeo's cavalry and naval units to pacify the south and the north.Gwanggaero the Great attacked and conquered Buyeo, Biryu-guk, the Later Yan, Malgal, and the Ainu tribes.