The government encourage trade and foreign influence and also encourage introduce of many regilions, such as Islam, Nestorianism (called The Luminous Religion or The Luminous Religion of Ta-chin in China), etc. Because of economic and political problem, Emepeor Tang WuZong (Li Yan)order to suppresse Buddhism. He believe the overdevelopment of Buddism, monks and temples had been a burden to the goverment because they didn't pay any tax. Also, Emperor Wuzong believed in Taoism. The construction of the Grand Canal was 805-610, over 4 years. Not completed in Tang Dynasty.