Tashan Weir, located by Mount Tashan southwest of Yinjiang Town, Yin County, was built by Wang Yuanwei, Administrator of Yin County, in the year 833. It was built in the upstream of the Brook Zhangxi (formerly named Daxi), is one of the four major water conservancy projects in ancient China (the other three being Zhengguo Aqueduct, Ling Aqueduct and Dujiang Weir). To the south of the Brook Zhangxi were rolling mountains, and to the north a vast plain. Standing near the southern bank of the brook was a solitary hill named Mount Tashan. Tashan Weir, 134.4 meters high and 4.8 meters wide, was built up with eighty and a half pieces of stone slabs measuring 2 to 3 meters long and 0.2 to 0.35 meters wide. Thirty-six stone steps were provided on both the left and right. The surface of the Weir is built with stone and the body of the weir is built with both stone and wood. It's also the major cultural relic under the protection of the state. Legend has it that there was a huge trunk of plum-wood lying in the Weir, firm as ever through over one thousand years, hence the name 'the Plum Beam of Tashan Weir."