He was the grandfather of Yeon Gaesomun, who was Dae Magniji and dictator of Goguryeo before its fall.
Historians have tried to translate this text, and have established that the Yeon ancestor may have been born at sea or near a river.
After the death of Yeon Taejo, his eldest son Yeon Gaesomun was refused his rightful positions by the other nobles of Goguryeo, and had to stage a coup that overthrew the King Yeongnyu at the time.
After Yeon Gaesomun's death, his sons ravaged the kingdom apart with their struggles amongst themselves.
With this, Goguryeo eventually fell to the Tang dynasty and the southern Korean kingdom Silla in 668.