Qing is very different from earlier Han Chinese dynasties which only used military means to subjucate nomads without proper measures afterwards therefor the pacification lasted very short, at best some decades. Qing wasn't ashamed of intermarriage or playing with "Babarians", it treated Mongols like Qin dynasty handling people of other warring states 2000 years ago, "you are conquered and now live as equals". Qing was willing to do such things because itself started as "Babarians".
Qing was not the first. Although the implementation may be different, Tang also leveraged the strategy of using nomads to fight nomads (and Han as well, albeit to a significantly lesser extent). After the complete and total destruction of the Turkic Khaganate, the Tang military continued to retain descended generals and soldiers of Turkic descent in its military for generations. An Lushan is believed to have been at least half Turkic.
Manchus were not barbarians. The Ming classified them as civilized subjects. Manchus lived in Chinese style cities, derived subsistence almost entirely from agriculture, and their culture lays fully within the Sinosphere. They were not steppe nomads like the Mongols, Turkics, Xianbei, or Xiongnu.