This is what the dragon is often called in Taoism, China's native religion. It's impossible to overstate the importance of the dragon in ancient China because not only was it a symbol of the Emperor and the spirit of the people, but until quite modern times the dragon was widely believed to be a perfectly real creature that controlled the weather, particularly the rains upon which the lives of millions depended.
People also believed that earthquakes were caused by treasure-guarding dragons stirring below ground. Floods were caused by the restlessness or anger of water-dwelling dragons and thunderstorms were due to the mating or battle of dragons in the sky, real Leviathans of flesh and blood who at any moment might fall and flatten the village below. There are many legends of this having happened and for proof in some parts of China visitors would be shown the creature's bones. These dragon (dinosaur) bones were believed to be potent medicine and where they were plentiful whole districts earned a living from grinding them to powder and exporting them.
Despite these occasional disasters, people did not consider dragons evil, on the whole quite the opposite. Dragons were revered as basically wise and gracious divine beings, great benefactors of humanity. There were some weather gods with human form, but they took second place to dragons. It was dragons who were believed to dispense the fertilizing rains so essential for the annual crop. Natural disasters were attributed to their carelessness, neglect or justified anger; so offerings to dragons were designed more to win their attention and favour than to appease any natural inborn malice.
These sacrifices appealing for the right measure of rain, were made at countless waterside temples in China. Every well, stream, river and lake in China had its temple, be it ever so small, where on the first and fifteenth day of the month (the new and full moons) the owner, or the people living nearby, came to make offerings to the dragon they sincerely believed to dwell in the water for much of the year.