The Hangeul alphabet is a big deal in South Korea: It's what replaced Chinese characters in the 15th century, it's the official script of both the North and South to this day, and it has its own national holiday. And that makes the discovery of King Sejong's hat, which was reportedly stolen by Japanese invaders some 500 years ago, all the more exciting. The AFP reports that tucked between the hat's layers were documents about the famed alphabet, which Sejong introduced.
A South Korean collector bought the "cicada-wing hat" in Japan last year and has since donated it to the government, a scholar tells the AFP. The notes inside—discovered between the hat's red lining and brown and gold exterior, which Yonhap reports bears images of a four-clawed dragon—are from at least two years earlier than the oldest known documents explaining Hangeul's creation. "This hat will help shed light on details on the creation of Hangeul and ancient royal costumes," says the professor.