Later, the Southern Song is overrun by the Mongols, and the Yuan dynasty adopts Zhu's Four Books as a required subject in the imperial exams. The exam system makes the Four Books required reading for Chinese intellectuals, and thereafter mainstream thinking centers around Zhu's interpretations of these texts. The spirit of the Four Books also percolates into Japan and Korea.
南宋亡於蒙古後，朱熹窮四十年精力註解的《四書集注》成為元代國子監考試科目，隨著科舉制度，四書成為知識份子必讀書籍，中國被營造成一個以四書為中心思想的世界，東亞的日本、韓國也深受四書精神潛移默化。