Qimen Weir is the famous ancient water engineering with more than 2000 years’ history. In the reign of Emperor Kao Tsu 7th (in 200AD) in Han Dynasty, Lin Xin was the Gengjie Leud.He began to block the river to build the dam. And he named it as Qimen. He led the water to the northeast and developed aerial farming and irrigated more than 80.000 mu land. Furthermore, he also built Wuyang weir and Caodu Weir, Which together with Qimen Weir are called three weirs of Qimen. He blocked the Longshu Water and irrigated land of 1.500 qing. In the reign of Emperor Xuande in Ming Dynasty (1426-1435), Liuxian, the leader of the county improved the plan; he enlarged the irrigated area and framed the new method of water using and managerial system. The people here benefited a lot from his policy for generations. People built the Sanliu Temple in order to commemorate Liu Xin, Liu Fu and Liu Xian; furthermore they also glorified them by singing their praises. Qimen Weir takes full advantage of natural slope, pond and the ditch to form the system of gravity irrigation. There are mountains and waters, so it is a good place for tourists. Sanyan Yuze is honored as one of the top 8 scenic spots.