There are four purposes for the Yongzheng dynasty to change the land into a stream: 1. Politically, the rulers of the Qing Dynasty wanted to cut off the local separatist forces, stabilize the localities and consolidate the centralization of despotism. E Ertai suggested changing the flow rate, which was the first consideration. For example, in November of the fourth year of Yongzheng, he said, "If we don't clean up here and stipulate the rules, even if we beat a few local officials and kill a few signs, we won't be in a hurry to treat the symptoms. If the disease is not removed, it will be difficult to persist in the end. ..... but we have to wait for the future, that is, ten or twenty years at the latest, but success is always good. " [68] Yin Zhen advocated changing the flow also for this purpose, because in his view, "everyone in the territory knows that the unification is in our dynasty, and those who know their sons and ministers dare not go beyond their ambitions" [69], so they should inform the lawless chieftain in a secluded corner to change the soil and return to the flow, hoping that "after this punishment, there will be decades of silence" [70]. Later, Daoguang's "Xuanwei County Records" made it very clear that the purpose of changing soil into streams was: "Song Taizu said:' Don't make people snore and sleep on the couch.' Husband snores and sleeps, how is arrogance? Today, changing the soil into a stream is only to appease the frontier. "[7 1]2. Militarily, the Qing rulers should strive for strategic locations, then control the southwest frontier and consolidate national defense. Due to the dangerous mountains and rivers in the southwest provinces, most of the strategic places were occupied by chieftains, so for military needs, the Qing government had to take chieftains instead. As far as Guizhou is concerned, its topography is extremely important in the southwestern provinces. During the reign of Kangxi, the governor of Guizhou, Tian Wen, said, "Without Guizhou, the arms of Guangdong, Guangxi and Sichuan can be grasped, and the words of Yunnan and Chu can be punished." [72] Therefore, "those who govern Guizhou have their own governance, and those who mess with Guizhou have their own chaos" [73]. Because of this, it took a long time for E Ertai to attack Guizhou for the first time. Among them, the campaigns of Changzhai, Guzhou and Du Jiang were all aimed at seizing military positions and controlling Guizhou to seize the southwest throat. For another example, the original local governments of Wumeng, Zhenxiong and Dongchuan in Sichuan are located at the junction of Shu, Yunnan and Guizhou provinces. "If we don't change the land, back to now, the junction of the three provinces will be disturbed" [74], so the three local governments will bear the brunt of the change. Later generations Wang pointed out when analyzing why he wanted to change the river: "the number of provinces in the scenic spot is wrong", which shows that "we must seize the danger and build a city". If there is danger, you will lose dependence; Israeli soldiers are frightening. Terrain, change a suitable one. [75]3. Economically, the rulers of Qing Dynasty should get more benefits from the southwest provinces. Although the feudal government paid tribute to the toast, it was often the toast who took a lot from the natives and gave little to the government. For example, when E Ertai reported the situation of Yuantu Prefecture in Yunnan in the fourth year of Yongzheng, he said: "The annual rice quantity is 100 stones, and today it should be 1,212 stones per year; The annual amount of silver is 36 Liang, and this year it will be paid 2348 Liang. For people who collect contraband goods, it is not a hundred times or dozens of times, but it is not as good as one or two, not as good as two or three. Wait, how can we win? "[76]. In addition, most of the land is occupied by toast, such as Yunnan and Guizhou," ten officials and three four, ten toast and six seven "[77]. In this way, the Qing government not only could not profit from it, but also needed to help each other. "It needs to allocate hundreds of thousands of taels every year." Therefore, "long time is real worry" [78]. In order to obtain direct economic benefits, the Qing government certainly had to change this situation. E Ertai once said that "the wages in the border areas are heavily subsidized", and Yin Zhen has mixed opinions: "The subsidies are not small" [79]. Wang said more clearly, "the trees in the scenic spot can't be used, ... the iron bones of Miao are important for a while, copper and silver are the country, and the medicinal bait is used for health preservation ... The collection of its products will also help the treasury in Weishan" [80]. It can be seen that the rulers of Qing dynasty also had strong economic demand for southwest China. 4. In terms of ideology and culture, the rulers of the Qing Dynasty should influence all ethnic groups in southwest China with the traditional ideas of the Han nationality, so as to "take foreign things as the center". This is urgently needed by the Qing government in order to better control all ethnic groups in southwest China. Therefore, people of all ethnic groups in southwest China should know the so-called "courtesy of monarch and minister" and "meaning of obedience" [8 1] and be willing to "obey" the rulers. Yin Zhen repeatedly stressed that all ethnic groups in Southwest China should "turn stubbornness into kindness" [82] and make them "imitate the style of the king". In a word, the purpose of the Qing rulers' reform of the land to the native land was to make the southwest minority areas unconditionally under their own rule, just like the mainland, and to achieve "great unity."