During that time, Mooyel, the Silla king forged a military alliance with Dong and vanquished Backjae, then he died the following year.
After the passing of the King, the prince Bubmin ascended to the throne and became King Moonmu. King Moonmu maintained the military alliance with Dong, vanquished the Backjae-Waih alliance and even occupied Kogurye. After that, he was victorious against the war with Dong and its attempt to occupy Korea. For the first time, there was peace on the Korean peninsula and Waih, which changed its name to Nippon, was fearful of Silla and paid tribute to Silla.
However, 5 years after the war, King Moonmu was ill and about to die. He left his last will, "A country shouldn't be without a king at any time. Let's have the Prince receive the crown before my coffin. Cremate my remains and scatter the ashes in the sea where whales live. I will become a dragon and thwart the Japanes invasion.
King Sinmun, who inherited the throne, cremated the remains of King Moonmu and scattered the ashes at Daiwong Rock in the East Sea. Moreover, the King Sinmun built and deicated Gomun Temple (the Temple of Appreciated Blessing) to his father, King Moonmu and built a water way for the sea dargon to come to and from the sea and land. King Sinmun also built a pavilion named Eegun, overlooking Daiwong Rock (Rock of the Great King), so that the succession of kings could pay their respects to King Moonmu from there.
A year after the death of King Moonmu, there was a rebellion of the aritocracy. This troubled King Sinmun, but in a dream, King Moonmu who turned into a sea dragon appeared with the former general Gim Yusin who turned into a god, and told him, "Blowing on a bamboo flute will calm the heavens and the earth."
King Sinmun awoke from the dream and rode out to the sea and received the bamboo flute.
It is said that blowing of the bamboo flute(called Monposikjuk) embodying the spirit of King Moonmu and the General Gim Yusin pushes back enemy troupes, cures illnesses, brings rain during drought and halts the rains in floods.
The reliefs found in two charteristic Silla bells, Sungduk Daiwong Sin Jong (the Bell of the Great King Sungduk, also known as Emilaih Bell) and Songwon Temple Bell are there because of this legend.
