Since which dynasty, "The Analects of Confucius" has been designated as a required textbook for imperial examinations?

The Song Dynasty - the reform period of the ancient Chinese imperial examination system

The imperial examinations in the Song Dynasty also made major reforms in the examination content. The imperial examination system in the Song Dynasty basically followed the Tang system, and the imperial examinations for Jinshi had serious drawbacks. Jinshi focused on pronunciation and rhyme, and were ignorant of the past and present. They only tried to memorize and recite the Ming Sutra, but their meaning was useless. After Wang Anshi was appointed as a political advisor, he began to reform the content of the imperial examination, canceling poems, verses, scriptures, and ink meanings, and focusing on classics, theory, and strategies to select scholars. The so-called meaning of the scriptures is similar to the theory. It is a short article, which is limited to using sentences in the scriptures as the title and using the meaning in the scriptures to develop. Wang Anshi's reform of the examination content was to understand the classics and apply them. In the eighth year of Xining, Emperor Shenzong ordered the abolition of poems, poems, scriptures, and Moyi to select scholars, and issued Wang Anshi's "New Meanings of the Three Classics" and treatises and strategies to select scholars. And the "Yi Guanyi", "The Book of Songs", "The Book of Books", "The Rites of Zhou" and "The Book of Rites" are called the Great Classics,

The Analects of Confucius and "Mencius" are called the Concurrent Classics. It is designated as a must-read for scholars taking the examination.

It is stipulated that the Jinshi examination consists of four sessions: one examination on major classics, two examinations on combined classics, three examinations on theory, and the last examination on strategies. The palace examination only tests strategies, with a limit of more than 1,000 words. Wang Anshi's reforms were opposed by Su Shi and others. Later, with the changes in the political struggle, the "New Meanings of the Three Classics" was cancelled. Sometimes it examines poems and poems, sometimes it examines the meaning of classics, and sometimes it is both, and the changes are uncertain.