In its formative years, Chinese civilization had been influenced by the contributing factors of the Yellow River region, the land of the loess. It is generally understood that the river, running through a vast area where the fine and porous soil accounts for the large silt content in its current, has a constant tendency to clog its own course and cause dikes to break and enormous inundations to occur. The problem cannot be dealt with locally. This predicament has a historical origin that can be traced at least to the Spring and Autumn period (722—481 B.C.), when in 652 B.C. Duke Huan of Qi convened his league of states. A mutual pledge by all participants is recorded in various sources as “not to execute improper dikes” and “not to hinder the water flow.” The stone inscriptions of his own achievements erected by the first emperor of the Qin dynasty (221—207 B.C.) are reproduced in The Records of History. One of the meritorious deeds that he credited to himself was the “neutralization of the barriers that obstructed water flows.” These and other references are evidence that China’s political unification, achieved in the B.C. era, had come under the pressing demand for a coordinated effort in dealing with the flood problem, which, over and above technical considerations, has remained in force for the past 2,000 years. 
