During the Tang Dynasty in 680 CE, Emperor Gaozong of Tang took his consort Wu Zetian on a tour of Mount Song. Wu again visited in 696 CE during her time as empress regnant to present gifts to the Shaolin monks. As this was her Wànsuì dēngfēng () regnal year, in commemoration she renamed Songyang County () Dengfeng. After the An Lushan Rebellion in the mid-eighth century, production in the Yellow River basin virtually ceased with miles and miles of the central plain lain waste. The Northern Song Dynasty established their capital at Biànjīng () [modern day Kaifeng] in 1105 CE whereupon Zhengzhou became one of the four imperial auxiliary capitals and was known as Xifu (). From the beginning the Northern Song Dynasty, education came into vogue and many Confucian academies sprang up across the country. At that time in Dengfeng, the Songyang Academy () below Junji Ridge () was one of the largest in China. Economic stagnation set in during the Jin dynasty with the only developments occurring in astronomy when Guo Shoujing and Wang Xun () set up a network of 27 astronomical observatories across China with Dengfeng at the center.