In antiquity, the South China Sea was also called "Chang Sea." "Chang" means a quantity of water so great that it is about to overflow. Chinese called the South China Sea the "Chang Sea" because it was so large that you couldn't see where it came to an end. The origin of the name "Chang Sea" is unclear, but it shows that the South China Sea was already of great geographical significance in the Later Han Dynasty.
　　 Subsequently, it became known by the name "Fei Sea," which means, "boiling sea." Because the South China Sea lies on the boundary between the sub-tropical and tropical regions, the water temperature is high. The waves are big, especially during the monsoon season. The big waves and bubbles look like boiling water, hence the name. This is indeed a vivid description; it also shows that the Chinese had sailed extensively on the South China Sea at that time. They also observed it and understood its features. The name "South China Sea" replaced "Chang Sea" and "Fei Sea" in the Tang or Song Dynasty. This is the name by which the sea is known today.