He was the father of Yeon Gaesomun, and was known to have taken an aggressive stance against the Sui dynasty alongside Field Marshal Eulji Mundeok.
The North faction consisted of Yeon Taejo, Eulji Mundeok and the military officials, while the South faction consisted of Grand Prince Go Geon-Mu, and the scholar-officials.
This resulted in Yeon Taejo's death without seeing a proper successor to his positions.
Yeon Gaesomun later led a coup that overthrew Go Geon-mu, who had become the 27th Taewang of Goguryeo.
Yeon Gaesomun led Goguryeo through one last period of glory before its fall in 668 at the hands of the Tang-Silla Alliance.