Tangun founded Kojoson (Ancient Korea), the first state of the nation and the first slave state in Korea, in the early 30th century B.C.

From that time on, the Korean nation has long lived in the same land with one blood and one language, creating the brilliant culture with a history of 5,000 years.

A number of historical records related to the mausoleum of King Tangun and memorial service for him can be found in old books like "Samgukyusa (History of the Three Kingdoms)" and "Sinjungdonggukyojisungnam (Revised Handbook of Korean Geography)".

During the Japanese imperialists' colonial rule, the Korean people created the Taejong faith (then Tangun worship). They also organized the society and association for defending the Mausoleum of King Tangun. The highest priest of the Taejong faith and many believers held memorial services for King Tangun every year.

President Kim Il Sung and Chairman Kim Jong Il took all necessary measures to find out the remains of Tangun, who was nearly faded away as a mythical being with the lapse of time due to the vicious moves of the Japanese imperialists and reactionary historians and to the incompetence of the feudal ruling circles, and glorify Korea as the country with a history of 5,000 years. When the remains of Tangun were unearthed and proved scientifically, the President and the Chairman saw to it that his tomb was reconstructed majestically as befitting the mausoleum of the ancestral father.

An event to commemorate the Foundation Day of Korea has been held at the Mausoleum of King Tangun in Kangdong County of Pyongyang, the capital city of the DPRK, every year.