Why did Kangxi prohibit the creation of Guandong?

After the Qing Dynasty moved its capital to Beijing, it designated the Northeast region as a special zone and strictly protected it. On the one hand, it is to prevent its "dragon vein" from being damaged. On the other hand, it was used to protect the specialties such as ginseng and dongzhu produced in the Northeast region that were needed by the royal family and nobles, as well as the paddocks used for collecting annual offerings and hunting during the emperor's patrol.

The wicker edge was built during the Kangxi period of the Qing Dynasty. It was a green fence built by the Qing court to mark the restricted area in order to maintain the "rise and fall of the ancestors", prevent the degeneration of the Manchus, and maintain the style of Mandarin riding and shooting. The entire Liubian is 2,600 miles long, with 20 side gates, 168 side platforms, and hundreds of water mouths (the place where Liubian crosses the river is called a water mouth). Like a giant dragon entrenching the northeastern land, it is called the Green Great Wall of Guandong. Willow edge is also called wicker edge because willows are planted on an earth bank made of soil that is three feet wide and three feet high. It was started in the third year of Chongde (1638) and basically completed in the 20th year of Kangxi (1681) (later expanded in some areas). The wicker edge is divided into three sections: east, west and north. Taking today's Weiyuanbao Town in Liaoning Province as the intersection, it extends to the southeast, southwest and northeast, forming a herringbone shape. The eastern section runs from Weiyuanbao Town to the southeast to Fengcheng City, Liaoning Province (1638-1661), and the western section runs from Weiyuanbao Town to the southwest to Shanhaiguan and connects with the Great Wall (1648-1654). The two sections are 975 kilometers long. It was earlier called "Laobian" and was under the jurisdiction of General Shengjing. After the 20th year of Daoguang's reign (1840), the Northeast was opened to cultivation and restrictions were relaxed, and the willow edge was completely abandoned[1].