According to the Samguk sagi, a 12th-century Korean history of the Three Kingdoms, Mobon was the eldest son of Goguryeo's third king Daemusin.
The Samguk sagi notes that Mobon's character was fierce and stubborn, and he incurred the resentment of the common people.
He named his son Ik the crown prince, but upon Mobon's death, there was a power struggle for the throne.
With this in mind, some scholars suspect that the records and public image of King Mobon may have been an attempt by the supporters of Taejo of Goguryeo to justify their coup de'tat.
These scholars further support the idea that the difference in last names in the early Goguryeo rulers is due to a shift in power among the Five Noble Families.