Introduction to Yangtian Cao: Yangtian Mountain is surrounded by ridges, with a flat land in the middle, four or five miles long, shaped like a manger. An earth beam in the middle divides the "trough" into two troughs, the north and the south. The south trough has the Black Dragon Cave; the north trough There are two caves, named Simen Cave and Bailong Cave, which are the places where water from the surrounding mountains is collected and released during the rainy season. During heavy rains, the mountains and rivers come from all directions. The two cave entrances are like huge funnels, and in the blink of an eye, the boundless floods are discharged. Drained completely.