Why did the Qing emperor choose Chengde as a summer resort and hunting place?

According to legend, Kangxi once went back to Beijing to pass by Chengde after looking for Shenyang in the north, and found that the Wulie River in Bangzi Mountain had beautiful scenery, so he had the idea of building a palace, so he renamed Bangzi Mountain Hammer Peak, and the Mongolian princes in this area gave land to build a summer resort. There are several reasons: 1, the Qing Dynasty was established for Manchus in the northeast, the climate in summer of beijing was hot, and Chengde was cool in summer, which was suitable for summer; Chengde is close to Mongolia. At that time, smallpox was prevalent in the Central Plains, and remote ethnic minorities dared not go to Beijing to avoid smallpox, so they went to Chengde Palace instead. 3. Chengde has a hunting ground for hunting;