[Why] The Yuan capital Dadu had a vast population and immense material consumption, but it was far from the grain-producing Jiangnan. The original meandering Sui-Tang canal was wholly unable to support the high-efficiency transport for the imperial capital. [What] The Yuan court conscripted laborers and broadly straightened the bends, opening up the Beijing-Hangzhou Grand Canal connecting Beijing directly to Hangzhou. At the same time it opened ocean shipping routes between Jiangnan and the north to transport grain. [Who] Hydraulic engineer Guo Shoujing was the core chief designer of the Beijing section (Tonghui River) of the Beijing-Hangzhou Grand Canal, successfully solving the water-source scheduling problem. Countless canal-digging transport workers paid their selfless sweat. [How] The canal's complete through-passage at one stroke solved the material-lifeline problem of the imperial capital Dadu, gluing the unified north-south politics tightly together. It became the greatest transport main artery in the medieval logistics history.
Why
The historic event of Yuan Grand Canal Integration represents a key developmental peak of the Huaxia dynastic system. The monumental logistics artery connecting the imperial north with the economic south. By establishing this moral or administrative benchmark, it continues to shape the structural and philosophical fabric of ancient Chinese statecraft.