The Essentials of Government in the Zhenguan Era (Zhenguan zhengyao) is a text that was compiled in the Tang dynasty after the death of the founding emperor, Taizong (r. 626-649). It circulated widely throughout East Asia but unlike many other texts that emanated from China it was often approached via the vernacular: there were translations into the Tangut, Khitan, Jurchen, Mongolian, and Japanese languages, but not into Korean. This article explores its reception in various East Asian societies and suggests that the use of the vernacular was determined by the role of this work as a practical manual