Heung-yo kingdom was founded when General Dae Yeon-rim gathered up people of Balhae. Dae Yeon-rim established the kingdom of Heung-yo at the western region of the former territories of Balhae. The fall of Heung-yo Kingdom was a very tragic one, as it fell at the hands of a traitor, who was a subcommander of Dae Yeon-rim himself. When the Liao invaded and attempted to conquer the kingdom, all castles but one were left standing. The doors of the last castle were opened from the inside by this subcommander of Dae Yeon-Rim, which ultimately caused the fall of the short-lived kingdom, and an unknown fate for Dae Yeon-rim and his loyal commanders.