At that time, there was no gunpowder and paper, so people burned bamboo to make it burst and make a sound to drive away the plague. This is of course superstition, but it reflects the ancient working people's beautiful desire for Aetna.
Firecrackers in the Tang Dynasty, also known as "blasting poles", probably burned a long bamboo pole piece by piece and made a continuous blasting sound. Nanchang poet Lai Hu's poem "Early Spring": "The new calendar is only half open, and the pavilion is still bursting. I wrote the scene of burning bamboo poles during the Spring Festival.
Later, after constant chemical experiments, alchemists found that saltpeter, sulfur and charcoal together could cause combustion and explosion, so they invented gunpowder. Some people put gunpowder in a bamboo tube to detonate, and the sound was louder, which fundamentally changed the ancient custom of burning bamboo. By the Northern Song Dynasty, people had fireworks wrapped in roll paper, and there was a distinction between Dan sound and double sound. It was renamed "artillery warfare" and later "firecrackers".