Throughout China’s millennia-old imperial history, the region of Manchuria used to be a nearly constant threat to its hegemonic power position in Northeast Asia. The traditional homeland of the (semi-)nomadic Xianbei, Khitan and Jurchen peoples served as a staging ground for numerous conquests of the Han-dominated areas. The latter group in its modern ethnic Manchu and dynastic Qing form had even created the largest China-based state ever. However, due to decades-long central policies, the region has drastically changed its political, cultural and even economic identity. The so-called Dongbei (Northeast) has emerged as the sum total of three provinces of Liaoning, Jilin, and Heilongjiang with a combined heavily Han-dominated population of a hundred million, and particular the role of “China’s rustbelt” due to the waning glory of once being the powerhouse of the People’s Republic’s initial modernization drive. In the latter sense somewhat similar to Ukraine’s notorious Donbass, this region still contains several important and compact national minorities. Once a formidable hard security threat to China-proper, today the principal minorities possess various domestic and even transnational political agendas that might be viewed as softer threats with a varying potential of becoming hard. This paper is a comparative exploration of the main threats related to the three largest local national minorities: the Mongols, the Koreans, and obviously the Manchus. A comparative analysis of the sinification and migration patterns, as well as historical, cultural and administrative shifts, would hopefully allow to evaluate their threat potential to contemporary China’s national and Northeast Asia’s regional security.