In ancient times, land transportation could only rely on human and animal power. The speed was slow, the transportation volume was small, and the cost and consumption were very large. Therefore, bulk goods are transported by water as far as possible. Most of the natural rivers in China flow laterally from west to east. However, after the Yellow River Basin was destroyed by war and the Yangtze River Basin was developed, China has gradually formed a situation in which the economic and cultural center is in the south, and the political and military center is in the north.