October 3 on the Gregorian calendar is Gaecheonjeol (개천절), or National Foundation Day. Gaecheonjeol literally means “the day on which the Heaven opens”, and is also known as Korea’s birthday.
This holiday celebrates the legendary formation of the first Korean state of Gojoseon in 2333 BC and this date has traditionally been regarded as the date of the founding of the Korean people.
Gaecheonjeol was designated as a national holiday in South Korea in 1909 and is currently a public holiday. The story of the founding of the Korean nation is based on the myth of Dangun in the Samguk Yusa (삼국유사 – Memorabilia of the Three Kingdoms).
The Dangun Myth
Hwanung (환웅), son of the Lord of Heaven, Hwanin (환인), wished to live on the earth to improve the welfare of mankind and descended from Heaven with 3,000 followers on Mount Taebaek on the Korean Peninsula in 2457 B.C. With the help of the gods of clouds, wind and rain, he improved many aspects of human life including agriculture, health, and the everyday welfare of people.
At that time, a tiger and a bear prayed to Hwanung to let them become human beings. Hwanung told them to keep themselves from the sunlight in a cave for 100 days and eat only mugwort and garlic during that period. The tiger soon gave up and left the cave, but the bear persevered and was transformed into a woman. Later, the bear-woman became Hwanung’s wife and gave birth to a son called Dangun Wanggeom (단군왕검).
Dangun later ascended to the throne, and in 2333 B.C., he founded the first Korean nation called Joseon, which means “morning calm”, an area covering Manchuria and the Korean Peninsula. It is referred today as Gojoseon (old Joseon) to distinguish it from the Joseon Dynasty established later in the 14th century.
Here is a video about the myth of Dangun:
Dangun is now regarded as the founder of the Korean nation and has become a symbol of national identity. The Dangun myth gives the Koreans a sense of national identity as a distinct race descending from a common ancestor.
Celebrations in South Korea
On the National Foundation Day, ceremonies are held at the shrines of Dangun in various places of South Korea. There is also an official ceremony held at the Sejong Performing Arts Center.