The four major inventions that emerged during the Sui and Tang Dynasties were gunpowder and printing.
Gunpowder:
Gunpowder was invented by Chinese Han alchemists in the Sui and Tang Dynasties, more than a thousand years ago. The study of gunpowder began with ancient Taoist alchemy. The ancients refined elixirs in order to seek immortality. The purpose and motivation of alchemy were advanced, but its experimental methods still had merits, which ultimately led to the invention of gunpowder.
Although alchemists have mastered certain chemical methods, their direction is to seek the elixir of immortality, and the invention of gunpowder is a by-product. Alchemists often burn sulfur, arsenic and other poisonous medicines before using them. "Fu" means to subdue. To lose or reduce the toxicity, this procedure is called "subduing fire".
Sun Simiao, a famous doctor and alchemist in the early Tang Dynasty, recorded in the "Method of Embedding Sulfur in the Alchemy": two liang each of sulfur and saltpeter, grind them into powder and put them in a silver pot or clay jar. Dig a pit in the ground, place the pot in the pit and level with the ground, and fill it with soil on all sides. Light three pieces of soap that have not been eaten by insects, then put them into the pot, and set off the sulfur and saltpeter. When the fireworks are no longer burning, stir-fry with charcoal. Stir-fry until one-third of the charcoal is gone. Then anneal. Before it cools down, add the mixture and put it down.
Printing:
During the Sui and Tang Dynasties in China, people combined the two methods of engraving seals and rubbing characters on carved stones, and invented engraving printing. The "Diamond Sutra" left by the Tang Dynasty is exquisite and clear, and is the world's earliest engraving print with an exact date (868). In the Song Dynasty in the mid-11th century, Bi Sheng invented movable type printing, which made printing widely popular. Chinese woodblock printing spread to Arabia around the 8th century AD. After the 11th century, it spread to Europe from Arabia and then to Egypt around the 12th century. With the spread of papermaking, paper successively replaced the papyrus of Egypt and India. Leaves and European sheepskins triggered huge changes in the world's writing materials. From the 14th to the 15th century, printing became popular in Europe.