He Yan's personal interpretation of the "Lunyu" was guided by his belief that Daoism and Confucianism complemented each other, so that by studying both in a correct manner a scholar could arrive at a single, unified truth. Arguing for the ultimate compatibility of Daoist and Confucian teachings, he argued that "Laozi fact was in agreement with the Sage" (sic). The "Explanations" was written in 248 AD, was quickly recognized as authoritative, and remained the standard guide to interpreting the "Analects" for nearly 1,000 years, until the early Yuan dynasty (1271–1368). It is the oldest complete commentary on the "Analects" that still exists.