Introduction to Sandaoguan: Sandaoguan leads to Jiaoshan in the south and Jiumenmen in the north. Three passes go straight into the sky, and the Great Wall hangs upside down on a cliff. The cliffs are steep, the peaks are high and the valleys are deep, making it extremely thrilling. How can we build the Great Wall if we don’t have the intestinal tract of a sheep and birds can’t find a place to fly? It has become a mystery through the ages.