One is that there was a fierce monster called Nian in ancient times, which went door-to-door every year1February 30th, foraging for human flesh and killing creatures. On the night of the thirtieth day of the twelfth lunar month, Nian came to a village. It happened that two cowboys were fighting for a whip. Nian suddenly heard the sound of whipping in mid-air and ran away in fear. It fled to another village and saw a bright red dress drying in front of the door. It didn't know what it was, so it turned around and ran away. Later, he came to a village, looked into the door of a family, and saw that the lights were brightly lit and dizzy, so he had to slip away again, with his tail between his legs. As a result, people realized that Nian was afraid of noise, red and light, and thought of many ways to resist it, such as setting off firecrackers, which gradually evolved into the custom of celebrating the New Year today.
Another way of saying this is that ancient calligraphy books in China put the word "Nian" in the Ministry of Grain, which means good weather and good harvest. Because cereal crops are usually harvested once a year. "Year" is extended to the name of the year.