In 214 BC, Qin Shi Huang, the First Emperor of the Qin Dynasty (221-206 BC), ordered the construction of a canal connecting the Xiang and the Li rivers, in order to attack the Baiyue tribes in the south. The architect who designed the canal was Shi Lu (Chinese: 史祿). It is the oldest contour canal in the world, receiving its water from the Xiang. Its length reaches 36.4 km and it was fitted with thirty-six flash locks by 825 AD and there is a clear description of pound locks in the twelfth century, which were probably installed in the tenth or eleventh century. Its design also served water conservation by diverting up to a third of the flow of the Xiang to the Li.