Four thousand, three hundred and forty-five years ago, in early October, the gates of Heaven opened over the White-Headed Mountain.
A Heavenly Regent (Hwanung) had asked that his father, the Lord of Heaven (Hwanin), grant him a beautiful peninsula to rule over, because he had seen that the people in that land had become badly behaved and he felt sorry for the place. At the holy White-Headed Mountain (Baekdusan) in the north of the peninsula, near a holy sandalwood tree, the Heavenly Regent established a heavenly city with his three chancellors, named Wind, Rain and Cloud, and 3000 followers.
[broken link! FIXME] There were a tiger and a bear living together in a cave on the mountain, and they saw the Heavenly Regent's city and were desiring to become human, and so they would pray each day at the sandalwood tree. Finally, the Heavenly Regent called the bear and tiger into audience with him, and told them that if they would do as he said, they could become human.
He gave them garlic and weeds (like daisies and mugwort) to eat, and told them to take only these items deep into their cave and wait 100 days, and they could become human. The tiger and bear went into the cave, but the tiger quickly grew tired of only eating garlic and weeds, and gave up his hope to be human and fled the cave. The bear persevered, however, and after 101 days, she awoke to discover she'd become a beautiful woman. She emerged from the cave and returned to the sandalwood tree.
Now that she'd become human, she wished to have a child, but her husband the tiger had abandoned her due to his lack of patience. So, again she would pray at the sandalwood tree, and after a time, the Heavenly Regent took her as a wife and she became pregnant and bore a child, who was named Sandalwood (Dangun), which also means Altar Prince.
The Prince Sandalwood moved to the Flat Land (Pyeongyang) and founded a city he named Morning City (Asadal). The kingdom was named the Morning Calm (Choseon).
More than four thousand years later, on October 3rd each year, the people of Morning Calm, who are the descendants of Prince Sandalwood, and who also call themselves the Great Nation (Han or Khan), memorialize the opening of Heaven by taking a day off from work.