The first book ever printed, i.e., not written or carved by hand, but set in movable type, was done so in China. We don’t know when the very first one was printed but they were being commissioned by 868 CE, when this Diamond Sutra (an Indian Buddhist text that was popular in Chinese Buddhism) was manufactured. It’s dedication says:
reverently made for universal free distribution by Wang Chieh on behalf of his parents on the fifteenth of the fourth moon of the ninth year of Xian Long (May 11, 868).