Introduction to the Lushan Cave Group: The Lushan Cave Group is the Yiyuan Cave Group. There are more than 100 large and small caves within a radius of 5 square kilometers with the Yiyuan Monkey Man Site as the center. They are all developed in the thick micrite limestone of the Middle Ordovician. They are large in number and particularly concentrated in distribution, and are called “the largest group of caves in the north” by experts.