This paper aims to reconsider the overlooked connection between Qing-Chosŏn relations and the persecution of Catholicism in late Chosŏn. There were numerous border-crossing cases related to ginseng poaching and illegal logging between the Qing and Chosŏn dynasties. With the threat of the spread of Catholicism in East Asia, the legal conception of the border transgression, however, also came to be applied to the people who devoted themselves to evangelism in Korea, including Chinese and European clergymen. All these ecclesiastics were executed, in contrast to earlier border-crossing cases and the suppression of Catholicism in Qing China. In the 1801 case of Chinese clergymen, Chosŏn authorities tried to legitimize the execution by applying a dubious imperial edict from the Yongzheng emperor, which shows the influence of Sino-Korean relations in the domestic purge. As for the European cases of 1839 and 1866, officials directly emphasized “illegal border-crossing” and “the case of 1801,” revealing the inseparable linkage between the suppression of Catholicism, border transgression, and Qing-Chosŏn relations. Additionally, Chosŏn authorities started to make a series of anti-Catholic laws, adopting similar nuances to its Qing Chinese counterpart. Based on Chosŏn laws and the discussions and adjudications of the aforementioned cases from interrogation records and chronological texts, this paper argues that the previous transgression affected anti-Catholic policies in Chosŏn; meanwhile, Chosŏn authorities had developed unique legal reasonings that distinguish them from Qing China, implying the existence of a polycentric nineteenth-century East Asia.