Early Korean Typography.

Moveable type was not invented by Gutenberg; that innovation is attributable to P’i Sheng of China, who used hardened clay letters between 1041 and 1048. Clay was not an ideal substance for printing type, but even cast metal letters were used centuries before Gutenberg. The credit for that major development belongs to Korea. The exact date is not known, but as Early Korean Typography notes we can be fairly certain it was after 1102 and before 1232.

Gutenberg would not have known of the Chinese and Korean use of moveable type, which is a major component of the printing process.