 The origin of the Yangtze River has been dated by some geologists to about 45 million years ago in the Eocene, but this dating has been disputed.The Yangtze flows into the East China Sea and was navigable by ocean-going vessels up from its mouth even before the Three Gorges Dam was built.The Yangtze is flanked with metallurgical, power, chemical, auto, building materials and machinery industrial belts and high-tech development zones.