the earliest account of the Tangun myth appears in the Samguk Yusa (Memorabilia of Three Kingdoms), a compilation of tales and myths recorded by the Buddhist monk Iryon. Written in the thirteenth century... the Samguk Yusa relates how Tangun descended from heaven in the year 2333 B.C. and landed under a sandalwood tree on Mount Paektu.Previously history in Korea was essentially the history of the court, and much prominence was given to the legendary Kija, who had fled China in 1122 B.C. and established a new kingdom on the Korean peninsula. After China was defeated by Japan in 1895, and newspapers were established in Korea, much discussion of how to look at Korea's past and move away from its links to China was undertaken. As Japan took over the Korean government, it became clear, as the court now lacked legitimacy, that court-based history could no longer be useful , so another focus was needed. That focus became the concept of the minjok, a concept that was becoming popular in Japan and China at that time as well. By focusing on the minjok, or ethnic nation, the court-based history could be side-stepped. At the same time, the focus on mythical progenitors shifted from Kija to Tangun.
The growing status of Tangun paralleled the increased use of the term minjok, as the two were often loosely tied together. The first person to join those two elements in an extended treatment of national history was Sin Chae-ho, an editorial writer for the Taehan maeil sinbo. The widespread use of the new term minjok, together with the heightened awareness of Tangun - two developments Sin himself had helped foster as a member of the Taehan maeil sinbo - offered him two powerful instruments for writing a new type of history in line with the period's intellectual shifts and answering the long-standing calls for a new national history. In a serialized article entitled "A New Reading of History" (Toksa sillon), published in 1908, Sin provided the first detailed historical treatment of minjok. This was a polemical piece, with no documentation, in which Sin organized the main issues with which all subsequent Korean historians would be concerned. Sin's work offered both a fundemental critique of conventional history and, by setting the minjok's bounds, began to create a vision of the nation as a historically defined ethnic entity.This religion was soon known as Taejonggyo (Great Ancestral religion).
Sin's move to position Tangun as the unrivaled source of national history was quickly taken up by his contemporaries. But whereas Sin presented the progenitor of the minjok as a historical figure, others were more eager to accept the claims made in the early myths that Tangun had descended from heaven. In the year after Sin published "A New Reading of History," a group lead by the nationalist Na Chol established a new religion that worshipped Tangun.
Some of the earliest public espousals of Taejonggyo doctrine appeared in the Hwangsong Sinmun, the longtime promoter of decentering China and an early user of minjok. Shortly after the religion was founded, the paper began to run editorials embracing the teachings of the "divine progenitor." These were the earliest public forays into national history written from the perspective of the Taejonggyo. "A Divine and Sagely History of Our Minjok," as one piece was titled, started with Tangun and spoke of the importance of commemorating and revering this history for Korean self-respect and autonomy. Even though it was impossible to ascertain the precise date of Tangun's descent - a point it was willing to grant its critics - the Hwangsong Sinmun urged its readers to commemorate the birthday of the founding father on the third day of the tenth month of the lunar calendar - what was to become known as the Day Heaven Opened (Kaechjonjol). All civilized countries, they were told, remember their founders. For Koreans to do so "will forever preserve the national character of our minjok, lead to harmony and solidarity, and will display our qualities as a civilized people."This Hwangsong Sinmun article was written in November, 1909, making the celebration of Gaecheongeol 99 years old.