What happened
According to the myth, the heavenly prince Hwanung descends to a sandalwood tree on Mount Taebaek. A bear and a tiger are told to endure a hundred days in a cave eating only garlic and mugwort; the tiger gives up, but the bear transforms after twenty-one days into the woman Ungnyeo. Their son, Dangun Wanggeom, founds Joseon — traditionally in 2333 BC.
None of this is documented history: the story is a founding myth, and its date belongs to tradition, not to the historical record.
Background
The legend is first fully recorded in the 13th-century Samguk Yusa, compiled under Mongol pressure — a time when Korean identity mattered acutely. Modern historiography treats the actual origins of Gojoseon, the state the myth explains, as a question for archaeology; the traditional date is symbolic.
Consequences
The myth became a durable identity anchor. South Korea marks the traditional founding on October 3 as Gaecheonjeol, National Foundation Day, and the traditional Dangi era count numbers years from 2333 BC.