It's convenient to take bus No. 5 or take a taxi from the city. It's right by the South Lake. No tickets, just a simple registration. There is a humiliating history here. In the 1970s and 1980s, the French attacked the Qing army in northern Vietnam. After the Qing army obtained the Zhennan Pass, the Qing government appealed to France for peace. France proposed opening a port to trade, so the Mongolian Customs came into being.