Tongrentang's truly edible bird's nest is made of several kinds of saliva from Jin Siyan, which are produced in the southern coastal areas of China, Viet Nam, Thailand, Malaysia, Indonesia and the Philippines. Jin Siyan and domestic swallow are different. Although smaller than the domestic swallow, the body length is only about 18 cm, but the ability to nest and raise chicks is extremely tenacious. Jin Siyan naturally condenses saliva, which looks like an ear, with a thick bottom and a thin side. The nest has neat periphery and rough interior, like a loofah net. The entire Tongrentang bird's nest is elastic and attached to the rocky cliffs. It has always had the reputation of "Oriental Treasure".