Introduction to the ruins of Yin Xi’s former residence: It is said to be Yin Xi’s residence. Yin Xi, a native of the Spring and Autumn Period, was well versed in celestial phenomena and was once the official of Hangu Pass. Legend has it that he once received Lao Tzu here. In the 29th year of Kaiyuan of Tang Dynasty (AD 741), Tian Tongxiu (a native of Taolin County), who joined the army of Prince Chen in order to please the emperor, reported to Emperor Xuanzong that a spiritual talisman had been dropped from heaven at Yinxi's former residence in Hangu. " Xuanzong was overjoyed and thought it was Laozi's gift to him, so he changed the reign name "Kaiyuan" to "Tianbao".