Mythologically, Dangun was the grandson of the gods, and the founder of Gojoseon, who set up the capital at Asadal. Legends say that around 4,340 years ago, Joseon was the name of the country that became Korea. So Dangun is believed to be an ancestor of the Korean nation. There was also a kingdom called Joseon later in Korean history, so Dangun's kingdom is called Go (meaning "Ancient") Joseon.
Once upon a time, Hwanung, the god Hwanin`s son, wanted to go down to the human world. Hwanin noticed that and let Hwanung go down to the human world with three amulets. Hwanung went to the Sindansu in Mount Taebaek, with his 3,000 followers. He managed the human world`s agriculture, morals, and 363 other fields of societal work. All these things went well.
One day, two animals visited Hwanung, begging him to change them to human beings. One was a tiger, and the other was a bear. Hwanung gave them an armful of divine wormwood and twenty cloves of divine garlic, and said: "Eat those for 100 days without being exposed to the sunshine. Then you will become human beings."
The two animals went to the cave and followed Hwanung`s orders. But during this process, the tiger couldn't endure this trial, and rushed out from the cave. On the other hand, the bear endured the trial and became a woman. But nobody was willing to marry her. So the bear woman prayed to conceive a baby at Sindansu. Then Hwanung transformed himself into human being for a while and married her. The bear woman gave birth to a baby. That baby was Dangun.
Dangun managed Gojoseon for 1,500 years, and after that long period, Giza succeeded to the throne. Dangun retired from the world and became a mountain god.