First use of metal moveable-type printing

The oldest documented use of moveable metal type dates from 1234, when the Korean Goryeo dynasty commissioned a civil servant called Choe Yun-ui to print a new edition of a book known as the Sangjeong Gogeum Yemun ("The Prescribed Ritual Text of the Past and Present"). This work consisted of a total of 50 volumes, and creating a wood-block printing plate for each page would have been impractical – particularly as the country's type-carvers were busy with another major government project. Instead, Choe Yun-ui came up with a printing method that used re-usable pieces of bronze type – one for each character. Work on the Sangjeong Gogeum Yemun was completed in 1250.

Earlier experiments with moveable type had been made in China during the 10th century, but these systems (which used ceramic or wooden type pieces) did not work reliably, and were soon abandoned. Early 12th century Chinese printers used metal type-pieces for anti-counterfeit measures in banknotes (the printing plate would have a slot for adding an additional symbol) but are not known to have employed them to create books.

While Choe Yun-ui's invention was undoubtedly useful, it did not have the ground-breaking impact that Johannes Gutenberg's printing press would have in Europe 200 years later. At the time, Korean was written with a logographic system, similar to Chinese, which reduced the potential benefits of moveable type. Making a book required the production of hundreds, even thousands, of unique characters, rather than copies of a 26-letter alphabet. In addition, the printing of books was controlled by the nobility and religious institutions, meaning that there was little need for a technology that enabled the production of books on a massive scale.

It is not clear whether or not Johannes Gutenberg's 1440 metal-type printing technology was in some way influenced by these developments in Korea. There is no direct evidence to suggest a connection, but Korean printing techniques had spread to nations along the silk road by the late 14th century, so it is not completely implausible.