The oldest letter written in the Korean alphabet, Hangeul, has been designated a cultural treasure.

The Cultural Heritage Administration(CHA) made the announcement on Thursday pertaining to the two-page letter written by Na Sin-geol, a military officer from the Joseon Dynasty, over 500 years ago that was discovered at his wife’s burial site in the central city of Daejeon in 2011.

Presumed to have been written in the late 15th century when Na served as an officer in Hamgyong Province, now part of North Korea, the letter requests that his wife look after the family and their farm, and asks her to send him items he needs at his post.

The artifact is valued as evidence that Hangeul, created by King Sejong in 1443 and promulgated three years later, was widely used by both men and women less than 50 years after its development.

It also offers a glimpse of linguistic life among ordinary people in the 15th century.