The Samguk sagi was completed in 1145, providing an early written record linked to Chuseok’s Gabae tradition.
This Korean historical work was compiled under King Injong of Goryeo by Kim Busik and other scholars. It is the oldest surviving official Korean history and is organized around the histories of Silla, Goguryeo, and Baekje.
The text describes Gabae, a Silla competition in which two teams of women competed in weaving during the seventh lunar month. Later Korean tradition connects this account with the historical background of Chuseok, though the modern festival developed through several layers of seasonal, family, and ritual practice.
The date is sometimes confused with the founding dates of the Three Kingdoms or with the later publication of other Korean chronicles. In this question, 1145 refers specifically to completion of the Samguk sagi.