The University of Wisconsin in Milwaukee is found to have a very rare copy of the “Daedong Yeojido” map of Korea.

Drawn up by geographer Kim Jeong-ho from 1861 to 1864, the Daedong Yeojido is a wood block print of Korea’s eight provinces. The map is usually printed on 22 folded sheets.

But unlike other copies found, the copy at the university has a total of 23 sheets, with the extra sheet confirmed to be an index.

The authenticity of the map was confirmed during a symposium on Korean maps of the 19th century, which was held at the university on Friday.

According to the American Geographical Society Library, which hosted the event, the copy was brought to the U.S. by George C. Foulk, who served as the U.S. Naval attaché to Korea between 1884 and 1887.